A Canon i-Sensys MF633cdw colour laser printer with scanner suitable for family use. (Photo: Canon)

Conclusion: A printer is no longer the necessity it once was. Frequency of use is part of the equation in determining what type of printer (if any) to buy. Often alternative sources can provide all of the printing resources needed. At other times, it may be prudent to invest in a colour laser printer with scanner.

Before rushing out to buy a printer there are several questions that should be asked, and answered.

  1. Who in the household needs to use a printer?
  2. What do each of these people want to use the printer for?
  3. What will their monthly production/ consumption be of premium colour print, regular colour prints and black and white prints?
  4. How much will each person need to scan objects?
  5. What alternative printing and scanning sources are available? at what price?

Unlike most of the products discussed until now, the answers to the above questions will show that most families will probably not need their own printer!

Ink in an ink jet printer will dry out, if not used at least once a week. Thus, most people with low usage requirements and an alternative printing source, will find that owning a printer is an unnecessary expense. While ink tanks attempt to make printing cheaper, they are only a solution if one is printing a large number of sheets regularly. Ink jet printers have a problem with drying out, regardless of how the ink is provided. Using an ink jet printer at home – say, once a month – will be frustrating and potentially expensive, as one has to cope with, and repurchase, dried out ink cartridges.

Laser printer toner cassettes do not dry out. They can be used minimally without problems. This is one reason why the author of this weblog post has purchased a laser printer, and disposed of the previous ink-jet printer. The laser printer is used mostly at the end of the month to make a paper copy of accounting documents, ingrained from long-forgotten accounting courses, that required people to keep a paper trail of transactions. Other people may not feel this need. Laser printers are more expensive to purchase than ink jet printers.

While many product reviewers are keen to emphasize the existence of monochrome (read: black & white) printers, these may be offering false economy. An inability to print a document in colour, may make the entire printing process irrelevant. A colour printer, can always print in black & white. Standard printing size is 8.5 inches by 11 inches in North America, and A4 in Europe. There is no need for most households to deviate from this. If there is, time should be spent sourcing where appropriate printers can be found, and used.

There are essentially three types of printing: Premium colour printing on glossy paper, for photographs and renditions of artwork, regular colour printing and black & white printing.

There are many brands of printers available. In my working life I have been subjected to too many HP printers that have had a number of technical issues, such as jambing. In my personal life, Epson has provided the most toxic experience, with its incessant requests to change ink cartridges to those that are Epson branded. In Norway, vendor lock in of this sort is illegal. I have used unofficial inks with Canon ink jet printers without problem. Currently, we are on our first set of original toner cassettes on our Canon i-sensyn MF633cdw printer, so this situation has not been tested, although unoriginal replacements have been purchased.

Many printers are classed as multi-function machines, a misnomer, as they usually add just a scanner. However, this ability to scan documents may tip the scale towards printer ownership. Once a document is scanned, it can be sent as an email attachment. Some printers can even offer faxing as an option. In the circles I frequent, faxes are cult items in the same category as telex machines. Both are irrelevant technologies. However, this is not the situation in all parts of the world, where faxes are still used.

A household printer should be connected to the household computer network of handheld devices, laptops, desktops and other computers. Normally, there is absolutely no need to have more than one printer in a house. There are several ways you can go about installing a network printer. However, two are most common. It can be part of the Wi-Fi network using an infrastructure controlled by your router, or it can be wired using Ethernet. Many printers are also able to read memory sticks, using a USB Type-A port. Not many printers are equipped with USB-C, yet.

There are several alternatives to owning a printer/ scanner. If one attends school or works for a living, there may be formal or informal arrangements for printing/ scanning documents. Some may require payment, others may not. A public library may provide an inexpensive service for patrons. Some office supply stores may also provide this service, charging for each page printed. Then there is FWB, a friend with benefits, which in some contexts may refer to something completely different, but here refers to a friend willing to let you use her/ his printer/ scanner. This may be precisely the benefit you need from a friend.

Another approach is that you become that FWB, and offer a printing service to people you know. This is not a money making proposition, but could be a way of reducing costs provided you are prepared to charge people for the services you provide. Collecting money is easy with an apps developed for this purpose: Venmo provides smart phone apps for payments in the US, Fooi does the same in Canada, and there is Vipps in Norway. Note: There may be more appropriate payment services that I am unaware of. If so, please let me know.

Below are links to spread sheets showing the calculations in LibreOffice format and Microsoft Office format, respectively, that can be downloaded and modified to suit your needs.

External Drives

In this weblog post several different types of external drives will be examined for different purposes.

Hard Drives

The main purpose for having external drives is to have off-site backup of files stored on a family Network Attached Storage server(NAS). It is to ensure that irreplaceable data is not lost by storing it in two separate locations. There are five drives with historic data that are permanently kept at a second location. This is because all that data is already on the NAS. Then there are six drives that are divided into two sets of three disks each. One set is taken regularly to the second location. Once there, the other set is returned home, and used to update files on a regular basis for the next couple of weeks. In a worst case situation, a catastrophic event would result in the loss of up to two weeks data.

Currently, hard drives offer lower price than solid-state drives when mass storage is needed, particularly in the range of 1 – 5 TB. Western Digital My Passport products are inexpensive, but offer good performance. This is due to using the USB 3.0 protocol, with its cable terminating in a Type-A connector. In addition it comes with an excellent disk controller. There is 256-bit AES Hardware Encryption available. The maximum transfer read speed is 174 MB/s , and the maximum write speed is 168 MB/s. In general it offers acceptable performance and reliability.

If one selects the Western Digital My Passport Ultra, there are two main differences. First, it uses a more robust metal enclosure. Second, the USB 3.1 protocol is used, with its cable terminates with a USB-C connector, but includes a Type-A adapter.

There are different manufacturers of HDD units including Samsung, Seagate and Toshiba. I have mainly kept to Western Digital, because none of my eleven My Passport drives have failed. In contrast, one of my two Seagate Backup Plus drives failed after minimal use. The second, remaining Seagate drive was quickly given away. Others are not so enthusiastic for My Passport drives. Slant ranks two versions of Seagate Backup Plus as the best drives. I have also considered purchasing Toshiba Canvio drives because of their compact physical size, but their smaller 3TB capacity makes them less practical for a person with large quantities of data to store.

Solid-State Drives

Solid-state drives (SSD) become expensive with large capacity disks. The Western Digital My Passport SSD is considerably more expensive, with storage capacity ranging from 256 GB – 2 TB. There is a USB 3.1 Type-C port and AES 256-bit hardware encryption. At the moment, the main disadvantage of these drives is price, which is more than four times the HDD equivalent.

Transfer speed is up to 540 MB/s. This speed increase is because SSDs access data electronically instead of electro-mechanically. This also improves their mechanical ruggedness. There is continued debate about the reliability of SSDs, with some finding them more, others less, reliable than HDDs. SSDs are sensitive to sudden power interruption, which can result in the loss of a drive.

While there are wireless drives, not all devices are equipped with Wi-Fi. Almost without exception, these devices are equipped with USB ports. Thus, there is no need to invest in wireless external drives.

Price for assorted 2 TB My Passport models (2020-02-08) in USD before taxes and shipping charges.

HDDUltra HDDWireless HDDSSDWireless SSD

USB flash drives aka memory sticks aka thumb drives

Flash drives are used for various purposes. Perhaps the most common use is for the transport of files when a person will not accompanied by their own laptop or other machine where the files are normally used. They are especially useful if one has to upgrade a number of machines to several different devices.

For these purposes one wants a fairly rugged and durable piece of equipment. Personally, I use a Kingston DataTraveler Elite G2 64GB flash drive. For the security minded, the main drawback of this drive is that it is not encrypted. If necessary, one could password protect sensitive individual files. One reason for selecting this drive is its metal casing, which is shock- and water-resistant. It reads at a maximum of 180 MB/s, and writes up to 70 MB/s.

The more security minded may want to consider a SanDisk Extreme Pro USB 3.1 available in 128 and 256 GB varieties. Its read and write speeds are extreme, up to 420MB/s and 380MB/s, respectively. It has an aluminum casing and comes with 128-bit AES encryption software. Its price is also extreme.

One of the main uses of flash drives here, is the storage of assorted Linux operating system distros. Each distro is placed on a new Kingston DataTraveler G4 16 GB flash drive. At one time, these were upgraded as new distro versions became available. However, after a couple of drive failures one learned that this was false economy. 16 GB drives are used not because one needs so much space, but because they are cheaper than 8 GB drives!

There are many times one needs to give people files on a flash drive. This has to be regarded as one of the normal costs of having relationships with people, in much the same way that serving visitors (invited or not) a cup of coffee is an investment in smooth social relationships. These G4 drives are the standard drives given to people. They are usually bought online, ten at a time.

SD Cards

While this section is labeled SD cards, some would argue that microSD cards would be a more appropriate heading. The original SD format is far too large for handheld devices. If a port on a device only takes original or mini-sized cards, passive adapters are available.

Computer Access & Assistance

Many people require access, assistive and/ or adaptive technology to function optimally. Here the Z-001 hospital bed, a form of adaptive technology, is being used to prolong the life of the 87-year-old dying widower, Kiyuro Takazawa, in Roujin Z, directed by Hiroyuki Kitakubo (1963 – ) and writen by Katsuhiro Otomo (1954 – ).

The terms disability/ handicap/ impairment/ incapacity/ infirmity/ invalidity and more, all refer to an inability to do something. Some of the words show greater sensitivity to the person involved, than others. There are lots of things no-one can do, such as turning one’s head 360 or even 180 degrees. This is not a disability because it is not in the human repertoire. There is a developmental curve in which infants transform themselves into adults. A child’s inability to do something is not a disability. At the other end of the age spectrum, people lose some of the abilities they once had. They are genetically programmed to develop disabilities. Yet, there are some abilities even for their age group, that most people have, but a few lack. Most people have an ability to distinguish red from green, but some are colour-blind.

Impairments may be congenital or originate from disease/ trauma. These can be placed in various categories. Cognitive impairments (head injury, autism, developmental disabilities) and learning disabilities, (dyslexia, dyscalculia, ADHD). Visual impairment (low-vision, complete or partial blindness, colour blindness). Hearing impairment (deafness, reduced hearing, hyperacusis). Motor/ dexterity impairment (paralysis, cerebral palsy, dyspraxia, carpal tunnel syndrome, repetitive strain injury).

One interesting place to begin an exploration of this topic is with the 84 minute long, 1991 Japanese animated science fiction action comedy thriller, Roujin Z (Old Man Z). This should provide an opportunity for people to decide what they want to avoid in terms of technology. According to British film commentator and sometime Vancouver International Film Festival programmer Tony Rayns (1948 – ), the film focuses on three primary issues: health care for the elderly, the stand-off between traditional values and modern technology and the Right’s covert plans to re-militarise Japan. (Rayns, Tony (1994). “Rojin Z/Roujin Z” in Sight & Sound. Vol. 4 no. 7. British Film Institute. pp. 52–53.) Only the third topic is uninteresting in terms of this post’s content.

Access, assistive and adaptive technology are three levels of technology. Accessible usually refers to specialized but low-level hardware or software features (or both) that help someone mitigate an impairment. It most often involves computing equipment that can be used by anyone, regardless of impairment type or severity.

Accessibility features such as text-to-speech, closed-captioning, and keyboard shortcuts make the use of computer technology less challenging for those with impairments. It also benefits those who are not sufficiently impaired to be considered debilitated. Basic tools are often provided by the operating system being used.

Visual aids include high contrast text, large text and screen readers in addition to desktop zoom features. In terms of keyboards, some people may prefer to use on-screen keyboards, or have visual or audio indicators on caps and numerical locks. Visual and audio alerts can also be used to provide event feedback, for typing assistance. Typing assistance may using sticky keys, that is, it may treat a sequence of modifier keys as a combination; slow keys, where there is a delay between when a key is pressed and when it is accepted; bounce keys, which ignores fast duplicate keypresses. For mouse keys, a keypad can be used to control the pointer; a secondary click can be simulated by holding down the primary key; a click can be triggered when a pointer hovers.

In addition to operating system features, there are many different apps available for both computers and handheld devices. eSpeak is a compact open source software speech synthesizer for English and other languages, for Mac, Linux and Windows. Formant synthesis allows it to work in many languages despite its small size. The speech is clear, and can be used at high speeds, but it is not natural or smooth, in contrast to larger synthesizers that rely on recordings of human speech.

Web accessibility involves making the use of the internet, and the World Wide Web in particular, easier. The World Wide Web’s ( Web Accessibility Initiative (WAI) provides not only resources but also web content accessibility guidelines and checklists. Here are links to some of the resources. The resources section is a good place to start. This can be followed up by consulting these resources: Strategies, standards, resources to make the Web accessible to people with disabilities; Web Content Accessibility Guidelines 2.0; Web Content Accessibility Guidelines 2.0 quick reference.

Assistive refers to more complex but standardized/ off the shelf objects or systems that are used to help individuals cope with their impairments.

Systems can remind people about turning off an oven or burners on a stove, closing the blinds and locking doors. While users can choose what events are to be reminded, many systems can be expanded to automatically perform these tasks or to turn on or off lights, or to adjust room temperatures. They can also remind users to take their medications. Reminder systems can be based on a handheld or wrist worn device. They can remind people about doctor’s appointments and taking medicine,

Another basic device is remote keyless entry systems which allows people to view who is at the door and then, should they choose, remotely open the door. The system can also lock doors and shut blinds to maintain privacy.

Automated pill dispensers can dispense only the pills that are to be taken at that time. Monitors are available to check their blood sugar levels, measure body temperature, blood pressure and pulse, and to dispense appropriate medications as needed, or to alert others. Robots can provide patients with medication and/ or nutrition.

Adaptive technology is specifically designed for people with disabilities. Sometimes, adaptive technology is regarded as a subset of assistive technology, referring specifically to electronic and information technology that are seldom used by a non-disabled person.

Input & Output Peripherals

Handheld devices and laptops do not need to attach input & output peripherals to operate. This is one attribute that makes them extremely portable and popular. Yet, neither portability nor popularity, in themselves, make them intrinsically better than less portable devices. Each device has to be examined in context of its intended uses. Unfortunately, Many portable devices make few concession to ergonomics.

This weblog post looks at peripherals that provide a better working situation for most people using a desktop device. Often, the same peripherals can be plugged into a laptop or a tablet. Advice on software to improve access or provide assistance will be provided next week (2020-03-10). Advice for people with specific impairments (vision, hearing, dexterity and/ or mobility) will be given in four weblog posts scheduled from 2020-11-24 to 2020-12-15.


The influence of the typewriter on the development of the computer keyboard cannot be underestimated. Yet, finding the typewriter’s original inventor is difficult. Journalist Joan Acocella (1945 – ) once estimated that significant contributions have been made to its development at least 52 times through history. However, the name typewriter began to be used in 1873 with the production of a Remington machine with a QWERTY keyboard.

Yet, the typewriter is not the only source of keyboard inspiration. The 1846 invention of the teleprinter/ teletype/ TTY by Royal Earl House (1814 – 1895) was also important, even if the 28 keys looked as if they belonged on a piano. A more typewriter-like keyboard for a teleprinter was invented in 1901 by Donald Murray (1865–1945). That same year Herman Hollerith (1860 – 1929) invented a keypunch, a machine that punches holes in paper.

The QWERTY keyboard was used because it was inefficient, making the machine less susceptible to jamming. There are keyboards formats that are faster. In 1936 Seattle educational psychologist August Dvorak (1894 – 1975) and William Dealey (? – ? ) patented the Dvorak keyboard, claiming it required less finger motion to write English, reduced errors, reduced repetitive strain injuries, increased typing speed and made typing more comfortable. People interested in learning why Dvorak is the better system are encouraged to read the Wikipedia article.

Part of the challenge of finding ergonomic keyboards is that some people may need additional features that only comes with software support. This means that if your specific host device is not configured for supported software, such users may not be able to use it optimally. Fortunately, in most cases, the keyboard will still work. For example, at the moment I use a Logitech K380 keyboard ($40) with my desktop machine, rather than a more ergonomic but more expensive ($130) Ergo K860 keyboard or the cheaper ($60) Ergo K350 model. I have found that the K380 fits my hands optimally.

Logitech Ergo K860 keyboard in operation. Photo: Logitech

Other people should examine the Ergo K860 to decide which elements of the keyboard, if any, they need. It should be noted that there are many other manufacturers of ergonomic keyboards than Logitech.

Logitech Keys-to-Go Bluetooth keyboard. Suitable for use in wet, dusty or more extreme environments. This one features the Nordic keyboard.

While ergonomics is important, it is not the only consideration in a keyboard. Despite dust control systems, a workshop can be a dusty place. Thus a less ergonomic, but waterproof and dustproof Logitech Keys-to-Go Bluetooth keyboard has been purchased for use in this environment.


The mouse has its origins in a trackball invented in 1946 by Ralph Benjamin (1922 – 2019). The first pointing device resembling today’s mice included a 1963 design study by Douglas Englebart (1925 – 2013), and its implementation as a prototype in 1964 by Bill English (1938 – ). The 1973 Xerox Alto is regarded as the first modern computer to utilize a mouse.

The main challenge with using a computer mouse is the position of the hand(s). The natural position of the hand is closer to vertical, as if holding a saw, than horizontal. Logitech claims the ideal angle is 57°. When the hand is forced to turn further over (counter-clock-wise for the right hand) mouse operation becomes less comfort and can provoke carpal tunnel syndrome and other repetitive strain injuries. Its use can become extremely uncomfortable for people with arthritis. Thus, it is important to design a mouse to fit natural hand positions and movements.

Logitech MX Vertical mouse. The mouse is aligned to 57°. (Photo: Logitech)

There are a lot of ergonomic mice available. However, one of the best that is suitable for a wide range of users is the Logitech MX Vertical. Logitech claims it is effective in reducing muscle strain, and in reducing hand movement. It is made from rubber and aluminum. It can be used as a wired USB-C cable, or wirelessly using Bluetooth or with a Unifying USB-A dongle. One of the real challenges is finding an ergonomic mouse for someone who is left-handed.

Graphic tablet

There are times when a mouse is the wrong pointing device to use to input data. This is especially true when trying to work with graphics. While there are many products available, One by Wacom is inexpensive and simple to use, but not something a professional artist would aspire to. It connects to a computer with a USB cable. The active area is about 152 x 95 mm. Even though Wacom advises users to download drivers to PC and Mac computers, these were already installed on Linux Mint. Its pen is ergonomic, lightweight (no batteries), balanced, pressure-sensitive and comfortable to hold. It allows people to sketch/ draw/ paint/ edit graphic works, including photos.

One by Wacom tablet and pen. Photo: Wacom


Speakers, headphones and earbuds are often tethered to a host device. Some few use a 1/4 inch phone connector, dating from 1877. More often a 3.5 mm connector is used. These date from the 1950s, but were popularized in the 1964 Sony EFM-117J transistor radio. At one time they were universally provided in tip-ring-sleeve (TRS) versions offering stereo audio. USB connectors are also available.

Cordless headphones/ earphones receive a radio/ infrared signals from a Bluetooth, DECT, FM or Wi-Fi transmission link. The headphone is only part of a powered receiver systems.

Headphones are especially important in spaces that are shared. While primitive versions existed by 1906, the first fully functional headphones were invented by Nathaniel Baldwin (1878 – 1961) in 1910, and sold to the US Navy. John C. Koss (1930 – ) invented stereo headphones in 1958. Earphones aka earbuds have existed since at least 1984. They too are increasingly cordless. However, because of the small size of their batteries, they often run out of battery power, if used for long periods.

At this point it should be pointed out that open office landscapes typically create un-wellness. To understand the full implications as to why open offices are such a bad idea, people are encouraged to read The Open-Office Trap.

Note: A more extensive work on headphones is planned for 2021.


The most sensitive and least adaptable peripheral is the display/ monitor/ screen. With a relatively shallow desk, an ideal screen size is probably 27″ (70 cm) or less. With a deeper desk, the size could increase to 32″ (81 cm), especially if there are a large number of windows that have to be open simultaneously. In-Plane Switching (IPS) technology should be used to provide accurate colour and a wide (up to 180°) viewing angle. It should be easy to height-adjust, tilt, pivot and swivel the display. In addition, the display should be flicker free and have reduced blue light, especially after dark. It can be advantageous for a display to have built-in stereo speakers. However, if the room is shared, headphones should be provided and used whenever two or more people occupy the room.

Benq promotes the flexibility of its business displays. Adjustment features, angles and dimensions can vary significantly from display to display. Illustration: Benq.

If the display cannot be positioned satisfactorily, then one must consider repositioning the desk. Ideally, a display should be placed at right angles to, or away from, windows and other light sources so it does not create/ reflect glare. Glare may cause eye strain. Once this is done, the display should be centred directly in front of the user.

Desks and chairs are usually not considered peripherals, but they are important for maintaining health, especially if one is going to be working with a device for many hours during the day. Many people find a height adjustable desk ideal, because it allows them to stand or sit depending on their mood. Height adjustments for growing children should made, say, two – four times a year. Adults should probably check things annually. Pregnant women may also want to make frequent adjustments.

Adjustments. Begin by sitting. First, adjust the chair seat height so that feet are comfortable on the floor. Adjustments to the back support can be made at the same time. Second, adjust the desk height so that hands feel comfortable on the keyboard and mouse. Note this position. Third, adjust the display/ monitor/ screen height so that it can be seen comfortably without strain. Place the top of the screen at or slightly below (0 – 30°) eye level. It should also be place about an arm’s length away from the user, so that the entire screen can be viewed comfortably. Fourth, stand and remove the chair. Adjust the desk height once again so the hands feel comfortable using the keyboard and mouse. Note this position. The display should need no further adjustment.

Purchasing/ Repurposing/ Disposal

Many people amass numerous peripherals over time. Thus, even when a peripheral fails, it is not necessary to buy a replacement immediately. This means that it is possible to schedule purchases over a period of time. Yet, because things can be damaged, such a schedule has to be flexible, allowing for a change in priorities.

Sometimes I become very disappointed with a piece of equipment, and want to return it. One reason I purchase products from the Norwegian electronics chain, Power, more than many other suppliers is their 30 day return policy. They allow people to return any product after 30 days for a full refund. This also applies to equipment that has been used. On the other hand, I also buy returned products from them at a discounted price.

Some of the recommended peripherals here have not yet been purchased, yet! Many are scheduled to be purchased at some time in the future. For example, my current display, a Samsung SyncMaster S27B350, was purchased 2012-11-09, so it is not even eight years old. It functions adequately, but is not height adjustable and does not have many of the other features discussed. Because I have some vision issues related to blue-light exposure, its replacement is nearing the top of the replacement schedule. It will probably replaced in the coming year with something similar to a Benq BL2780T. The Samsung display will be repurposed. It is far too good to simply discard. It will probably find a new home in the workshop, where it will still be used, but not so extensively.

Another alternative is to give products away to people who would otherwise be unable to afford them. However, I do not use other people as recycling stations for products that have met their end of life. These are disposed of at the local recycling station. Here, there is even a safe, for the proper disposal of media containing data.

Power supply/ charging

Deutschen Post electric vans in 1953-09-29 in Berlin. Electric vehicle batteries can be used to provide emergency electric power during power outages, to ensure that all necessary computer controlled functions in a house continue to operate.

Computer devices are dependent on electricity to operate. Increasingly, devices use battery storage/ power, to gain a temporary independence from the electrical power network. Various forms of small scale, local energy production (solar, wind) can even lead to a more permanent independence. However, not everyone is in a position to become permanently independent from the grid.

An electrical power blackout/ cut/ failure/ outage is the loss of electrical power somewhere in the network affecting the supply to an end user. These may be caused by faults/ damage at power stations, substations, transmission lines, short circuits, circuit breaker operation. A transient fault is a temporary loss of power, that is automatically restored once the fault is cleared. A brownout is a drop in voltage in an electrical power supply. Brownouts can cause operational problems. A blackout is the total loss of power to an area. They may last from minutes to weeks depending on circumstances. Rolling blackouts are planned blackouts that occur when demand exceeds supply. It rotates customers, so that at any given time some receive power at the required voltage, while others receive no power at all. Preventative blackouts are also used as a public safety measure, for example, to prevent wildfires around poorly maintained transmission lines.

Batteries in electric vehicles as well as solar panels are ensuring that there is always a minimal amount of electric power available, even if there is a grid related blackout. Circuits have to be designed so that electricity is not fed into the grid at these times, because that power could represent a hazard to people working on the lines to restore power.

Desktop and Tower computers

There are many different form factors used to make desktop and tower computers. These motherboard specifications determine dimensions, power supply type, location of mounting holes and ports. This ensures that parts are interchangeable over time. Two are especially important. The ATX specification was created by Intel in 1995, and is still the most popular form factor. Here the power supply offers several different voltages to meet the specific needs. These include +3.3 V, -3.3 V, +5 V, -5 V, +12 V and -12 V. There were and are attempts to offer just 12 V, but this reduces the selection of components available.

This type of computer has a power supply built into the computer case. It is suitable for power intensive assignments such as gaming or video rendering. Some can provide 500 W of power. The tower format is especially attractive if a large number of expansion cards are needed. One challenge with these is the need for active cooling. Fans can be noisy. The open nature of the case means that it will attract and accumulate dust, which will have to be cleaned at regular intervals.

The Mini-ATX family of motherboard specifications was designed by AOpen in 2005 with Mobile on Desktop Technology (MoDT). This adapts mobile CPUs for lower power consumption. With a simple but effective thermal design, it is suited for passive cooling, making it virtually silent. Manufacturing costs and overall operating power requirements are lower relative to active cooling designs. A DC-to-DC converter removes the power supply from the case, reducing system size. This type of computer is suitable for general use. The number of expansion cards is limited.


Almost all modern laptops use Lithium Ion (LiIon) batteries and use 19 V chargers. Each battery arranges LiIon cells in series. A LiIon cell has a maximum charging voltage of 4.2 V, although slightly more voltage is applied in practice. Voltage needs: One cell = 4.2 V; two cells = 8.4 V; three cells = 12.6 V; four cells = 16.8 V; five cells = 21 V. A charger uses switched mode power supply (SMPS) to convert the supply voltage to required voltage, sometimes using a boost converter (steps voltage up), but usually a buck converter (steps voltage down). A 19 V buck converter could charge up to 4 cells in series. When a LiIon cell is close to fully discharged it’s terminal voltage is about 3 V. A buck converter can accommodate this reduced voltage to maintain its charging efficiency, which can exceed 95 %.

Handheld Devices

There are three charger plugs in common use on handheld devices: micro-USB-B, USB-C and Apple Lightning. A cable will typically have a connector for one of these standards on one end, and a standard USB-A 2.0 connector on the other, that can be plugged into a charger, which – in turn – is plugged into a wall socket.

The micro-USB and lightning connectors will likely disappear in Europe, as the European Union has mandated use of a common charging connector, which will probably end up being USB-C.


As stated in an earlier post, USB originally allowed power to flow downstream from a Type-A connected device to a Type-B connected device. This situation has changed with the introduction of USB-C connectors, which combine A and B characteristics. It is not easy to see where power is flowing.

Type of DeliveryCurrentVoltagePower
Low Power USB 3.0150 mA5 V0.75 W
High Power USB 3.0900 mA5 V4.5 W
Battery Charging 1.25 A5 V25 W
Standard USB-C3 A5 V15 W
Power Delivery 1.0 Micro-USB3 A20 V60 W
Power Delivery 2.0/3.0 USB-C5 A20 V100 W

One of the most common devices needing power to operate are external drives. For example, Western Digital My Passport external hard drives that feature 2.5 inch drives, are powered by the computer, using a USB Type-A connector for data and power. In contrast, Western Digital My Book external hard drives feature 3.5 inch drives, that also come with a USB Type-A connector for data, but with an AC adapter with wall socket plug for power.

USB Battery Charging defines a charging port, which may be a charging downstream port (CDP), with data, or a dedicated charging port (DCP) without data. Dedicated charging ports on USB power adapters can run attached devices and battery packs. Charging ports on a host are labelled such.

In the computer world, one is perpetually in a transition period. There is always something newer and potentially better, and something older but tested and, hopefully, more reliable. Thus, a Western Digital G-Drive comes with three cables: USB-C to USB-C, USB-C to USB-A and a power cable that attaches to an AC power adapter. For computers that can provide power over a USB-C connector, only the first cable is needed. For computers without USB-C power, this first cable connects the AC adapter to the G-Drive, with the second cable connects the G-Drive to the computer.

Power over Ethernet (PoE)

With domotics (smart houses) becoming increasingly popular, it is becoming increasingly advantageous to install and use Ethernet cables to ensure devices are able to communicate effectively. While some switches only provide data transfer, many switches offer power, using one of the many Power over Ethernet standards.

There are two different approaches to providing power. Power sourcing equipment (PSE) that provide power on the Ethernet cable, typically a network switch, is called an endspan or endpoint. The alternative is an intermediary device, a PoE injector, also referred to as a midspan device.

A powered device (PD) is any device powered by PoE. One common device is a room controller which has sensors collecting data about a room, and actuators such as a solenoid capable of opening and closing a heating vent. In the future many computing devices should be able to receive power directly from an Ethernet cable.

PoE is expected to become a DC power cabling standard, replacing individual AC adapters in a building. While some are concerned that PoE is less efficient than AC power, others argue that it is a better solution because a central PoE supply replaces several/ many AC circuits with inefficient transformers and inverters, compensating for any power loss from cabling.

Standard 802.3af Type 1at Type 2bt Type 3bt Type 4
Power at PSE15.4 W 30 W 60 W 100 W
Power at PD 12.95 W 25.530.0 W 51 W 71 W
Voltage at PSE44.0–57.0 V50.0–57.0 V[50.0–57.0 V 52.0–57.0 V
Voltage at PD 37.0–57.0 V42.5–57.0 V42.5–57.0 V41.1–57.0 V

Inductive Charging

Inductive charging involves wireless power transfer, using electromagnetic induction to provide electricity to portable devices. The most common application is the Qi wireless charging standard. Devices are placed near an inductive pad. There is no need for electrical contact with a plug, or for devices to be precisely aligned, for energy transfer. Advantages of wireless charging include: corrosion protection and reduced risk of electrical faults such as short circuits due to insulation failure; increased durability, because there is significantly less wear on the device plug and the attaching cable; No cables; Automatic operation.

There are some disadvantages: Slower charging, devices can take 15 percent longer to charge; more expensive because of drive electronics and coils in both device and charger; there is a certain inconvenience cause by an inability to move a device away from its pad, while it is being charged; there is an assortment of incompatible standards that not all devices support; devices get hot when charging, and this continued exposure to heat can result in battery damage.

The Qi standard is supported on devices fro Apple, Asus, BlackBerry, Google, HTC, Huawei, LG Electronics, Motorola Mobility, Nokia, Samsung, Sony and Xiaomi. Released in 2008, the Qi standard had by 2019 been incorporated into more than 160 handheld devices.

Uninterruptible Power Supply

An uninterruptible power supply (UPS) provide electricity to an attached device if the main supply becomes unavailable. The duration of this protection varies. This is particularly important for desktop and server devices that do not have built-in batteries, in contrast to those with batteries, found in handheld devices and laptops. Even if a UPS is designed for mission critical equipment, it can be nice to have in a residence. Perhaps the most important device to connect is to a UPS is the router, to allow communication outside the residence. The local internet service provider (ISP) should have the rest of the network protected with their own UPS. What they actually provide varies.

Data or voice communication with a handheld device on cellular network can be the most effective way of communicating in an emergency situation, during a blackout. This is because the cellular base stations should have their own backup power sources, allowing them to operate normally.

Surge Protection

All electronic devices should be protected against surges = situations where voltages increase above specified levels, even if just for one or more seconds. Surge protectors can prevent this form of damage. This is probably best provided by having surge protection built into the circuit-breaker box.

Video Connectors

Some technical journalists are more dramatic than others. One described a display/ monitor/ screen as a window opening onto the soul of a computer, and the purchase of an appropriate one, a make or break experience. Both statements are exaggerations. Within a given budget, one must attempt to optimize the value of each component, and find a compromise.

There are several terms that will have to be understood to appreciate video connectors. Source, here, will be used generally to describe a machine producing a video signal, possibly through the internet, or stored as a file, or produced by a program. A display is a video screen capable of showing video images. A source is usually connected to a display using a cable. The ends of the cable, as well as the physical ports on the machines are connectors.

Most of the time graphic content on a display is something relatively static, including a desktop image, a text being written, or a list of files. At other times, the content may be more dynamic, such as a video film or a game.

A video connector is often overlooked because it is smaller than a display. Yet, it determines which displays can be used. This applies to laptop as well as desktop machines, home media centres, and handheld devices. There are a lot of standards associated with computer displays. Wikipedia lists 69 display standards, 22 signal and 32 connector standards. Fortunately, most of them can be forgotten as relics of the past.

One of the challenges with writing about video connectors is that there are several groups of intensive video users, who have specific demands. Some of these people are video editors, others are film fanatics, but most are gamers. They probably know very precisely what they want, and have other sources for advice. Intensive users will probably want to use a DisplayPort, version 2.0 on both source and display, connected using an ultra-high bit rate 10 (UHBR 10) cable. Mac users with USB-C connectors will want to connect to USB-C displays. With these extremists out of the way, the rest of this weblog will consider the needs of more ordinary users.

Some comments about specific video connectors

In computing’s Middle Ages, a Video Graphics Array (VGA) connector emerged in 1987. It was used on video cards, computer displays, laptop computers, projectors and even high definition television sets. Later, a smaller mini-VGA port was sometimes provided on laptop computers. This connector is still found on large numbers of sources and displays.

The Digital Video Interface (DVI) was designed to replace VGA in 1999-04. It can transmit uncompressed digital video in three modes: DVI-A (analog only), DVI-D (digital only) or DVI-I (digital and analog). It is backward compatible for use with VGA displays.

High-Definition Mulitimedia Interface (HDMI) dates from 2002-12. It is backward compatible with DVI-D and DVI-I, but not DVI-A. There are five types of connectors in use Type A = standard-HDMI; Type B = dual-link-HDMI (never used); Type C = mini-HDMI; Type D = micro-HDMI; and Type E = Automotive Connection System (ACS).

DisplayPort dates from 2006-05. It is backward compatible directly or indirectly, with all of the previously mentioned connectors. All DisplayPort cables are compatible with all DisplayPort devices, but may have different bandwidth certification levels (RBR, HBR, HBR2, HBR3). The major difference between DisplayPort and HDMI, is that while HDMI originated with consumer electronics, DisplayPort was oriented towards computer standards, especially at the more expensive end of the market. While there are several other DisplayPort connectors, only the Full-size DisplayPort and Mini-DisplayPort connectors will be discussed further.

What types of connectors are being used on each machine? Machines can be divided into sources and displays. Sources include different types of handheld devices (aka mobile/ cell phones, tablets), laptops, desktops and media players. Displays include monitors, televisions and projectors.

If any sources or displays support only VGA or DVI connections, these units should be considered for replacement. Modern TVs and displays have HDMI ports, DisplayPorts and/ or USB-C ports. Laptops typically have HDMI, micro-HDMI, standard DisplayPort or Micro-DisplayPort or, increasingly, USB-C ports.

The easiest connections are between machines that use the same family of connectors. It doesn’t matter what type of DisplayPort plug one is using, as long as the connector ends match those on the devices. One should buy cables with the certification level of the most advanced device (source or display).

A similar situation occurs with HDMI. The ends have to match, and the cable quality should mirror that of the best machine.

If any source equipment features DisplayPort Dual-Mode (DP++) this is a standard which allows DisplayPort sources to use simple passive adapters to connect to HDMI or DVI displays. Again, it is a relatively simple solution.

If both source and display have HDMI ports, an HDMI cable can be used. If different technologies are used an adapter, such as HDMI-to-DisplayPort, or vice versa, can be used. Similarly, there are cables with VGA, DVI, Micro-DisplayPort, DisplayPort or USB-C connectors at one end and HDMI at the other end.

A USB-C to HDMI / USB-C/ USB 3.0 multiport adapter is practical for computers using USB-C for AV output to displays, televisions and projectors, with video resolutions up to 4K (3840X2160P/30HZ). Source devices include MacBooks, Chromebooks, as well as several Windows and Linux devices.

Using this approach with laptops gives all of the disadvantages of a desktop without any of its the advantages. The laptop may not have enough ports for everything. It can be time-consuming and frustrating unplugging then reattaching peripherals after every move.

Previously, docking stations solved these problems. Peripherals, such as keyboard, mouse, display were plugged into the docking station, along with the laptop. Unfortunately, these were often brand and sometimes even model dependent. General-purpose docking towers are now available.

Handheld Devices

A Mobile High-Definition Link (MHL) adapter and a standard-HDMI to standard-HDMI cable is used to connect Android devices to HDMI displays. Here are the steps to follow.

  1. Use a MHL (micro-USB to standard-HDMI) adapter.
  2. Plug the male micro-USB (small) end of the adapter into the Android device.
  3. Plug one end of a HDMI cable into the MHL adapter.
  4. Plug the other end of a HDMI cable into a TV.
  5. Turn on the TV.
  6. Change your TV’s input to the relevant HDMI port.
  7. Wait for the Android screen to display on the TV.
  8. To work the depicted adapter needs a 5V 1A external power supply (5V 1A) to.power the adapter and to charge the Android device. Plug the charger’s male micro-USB end into the female micro-USB port on the adapter.
  9. Note: When using such an adapter for the first time, the phone must be rebooted after the adapter is connected to the phone, otherwise there will be no HDMI output.

Similar procedures need to be followed to connect an iPhone Lightning connector to a HDMI connector on a television using a adapter. Once again, but depending on the adapter, it may be necessary to have the charger plugged into the adapter for it to work. Others only need to be plugged in if the iPhone needs to be charged.


As stated in the previous weblog post, the future of video connectivity is the USB4 protocol and the USB-C connector. While every USB-C port looks the same, they do not all provide the same functions. This is especially true for both power and video. Its main advantages include high data/ video throughput, and ability to transfer electrical power. This means that USB-C monitors will get power as well as data from the source device they are connected to.

Randy Suess (1945 – 2019)

Randy Suess in 2004 as he appeared in BBS: The Documentary. Photo: Jason Scott

This weblog post is published on the 42nd anniversary (2020-02-16) of the opening of the CBBS (1978-02-16), the world’s first bulletin board service. It also commemorates the life of Randy John Suess (1945-01-27 – 2019-12-10). Born in Skokie, Illinois, Suess served for two years in the U.S. Navy, before attending the University of Illinois at Chicago Circle. He worked for IBM and Zenith.

In the 1970s, Suess was an amateur radio operator, with call sign WB9GPM. He was an active member of the Chicago FM Club, where he helped with maintenance on their extensive radio repeater systems.

However, Suess is most famously remembered as the co-founder and hardware developer of the first bulletin board system (BBS), along with partner and software developer Ward Christensen (1945 – ). They met as members of the Chicago Area Computer Hobbyists’ Exchange, or CACHE about 1975. Development of the BBS started during the Great Blizzard in Chicago, and was officially online (an expression not used at the time) as CBBS = Computerized Bulletin Board System, on 1978-02-16.

The early development of this and other bulletin board systems is documented in a previous weblog post, and more extensively in BBS: The Documentary an 8-episode documentary series created by computer historian Jason Scott, made from 2001-07 to 2004-12.

The CBBS consisted of a S-100 computer with an 8-bit, ca. 1 MHz processor, 64kB RAM and two single-sided 8″ diskettes each holding 173 kB formed the basis of the system, along with a Hayes MicroModem 100 running at 300 baud. The operating system was CP/M, but it ran other software was written in 8080 assembler, and automatically loaded whenever someone dialed in at: 312-545-8086.

Attention to detail was important for the survival of the system. The floppy disk drive motors ran from mains electricity, and quickly burned out if left on. So the system was modified by Suess to turn itself on when the phone rang, and to keep going for a few seconds after the caller had finished to let the computer save its data, and then quietly go back to sleep. A unique feature of CBBS, was that if callers typed inappropriate words, these would be recognized and the system would log the caller out. Entering too many unproductive keystrokes would have the same effect.

Suess hosted CBBS, because his house in the Wrigleyville section of Chicago could be called without paying long-distance charges by anyone in Chicago. By the time the system was retired in the 1980s, its single phone line had logged over 11 000 unique users, and received more than 500 000 calls. A version of CBBS has run periodically, more than forty years after its inception, demonstrating the state of technology at the end of the 1970s.

Because of his interest in Unix systems, in 1982 he created the world’s first public-access Unix system, then called “wlcrjs”. In 1984 this became Chinet (Chicago Network), which connected to the internet through a satellite radio. It ran on one of the earliest Compaq portable machines, with a 4 MHz 8088 processor, 640kB of memory, and a 10 MB hard drive.

In the early days of Chinet, the Internet was still a research tool, unavailable to the general public. E-mail and newsgroup accounts were obtained from a university computer or a BBS-like system. There were no ISPs (Internet Service Providers). E-mail and newsgroup postings were relayed from one computer to the next using UUCP (Unix-to-Unix Copy), a suite of computer programs/ protocols allowing remote execution of commands and transfer of files, email and netnews between computers, mostly at night, mostly over regular telephone lines at 1200 or 2400 Baud. The entire content on the internet was so small that it could be downloaded in a single evening. This meant that Chicago area users could browse a global collection of data without paying long-distance telephone rates.

In the late 80’s, Chinet had 12 dialup ports for between 300 and 600 active users. Later these were replaced with 22 phone lines that connected to a bank of modems, operating at considerably higher speeds. Eventually, the UUCP model became obsolete, with more companies getting direct Internet access, and ISPs offering inexpensive access to consumers. Chinet’s dial-up port usage started to decline.

Chinet then started using PicoSpan to replace its BBS software. Eventually, yapp (Yet Another Picospan Program) replaced PicoSpan and remained in use until Chinet migrated from Unix shell-based access to web based interfaces in the late 1990’s.

Despite a fire in 1996-05, Chinet still exits today, entirely web-based, running Simple Machines Forum software on a Debian GNU/Linux system.

Suess was married twice, first to Agnes Kluck and then to Dawn Hendricks, both marriages ended in divorce. He had two daughters, Karrie and Christine and one son, Ryan.

Randy Suess died 2019-12-10 in Chicago, Illinois. Currently, CBBS is operative, with information available about Randy Suess and his death.

Full disclosure: I am a registered user of CBBS/ Chinet, Chicago.

Universal Serial Bus

Older USB connectors are being replaced with USB-C (bottom right). Photo: Stéphane Mottin.

Conclusion: If you are considering investing in new computing devices carefully consider ones equipped with USB-C ports. This is the technology of the present and future. USB-A, USB-B, Mini-B and Micro-B connectors are relics of the past. However, devices with them should not be discarded. Cables with two different USB types on each end enable interconnectivity.

The Universal Serial Bus (USB) standard simplifies and improves the interface between a host computer and peripheral devices, with minimal operator action. Its interface is self-configuring. Connectors are standardized, so any peripheral can use any available receptacle. Usually there are no user-adjustable interface settings. The interface is “hot pluggable”, so peripherals can be used without rebooting the host. Small devices can be powered directly from the interface. Protocols for recovery from errors are defined, increasing reliability.

The USB standard specifies cables, connectors and protocols for connection, communication and supplying power to and between computers (Host or A-side) and peripheral devices (B-side). Peripherals include external disk drives, keyboards, mice and printers. However, they are not the only connectors. Screens typically use HDMI and other video connectors, the subject of a later weblog post. Similarly, Ethernet cables are preferred for connecting desktop computers and other devices to computer networks.

Today, most new Android handheld devices aka smart phones use USB-C (type C) connectors for charging and data transfer. Older Android phones have a Micro-B port. Apple iPhones (since iPhone 5) and most iPads use a Lightning connector. While the USB-C and Lightning look very similar, they are not interchangeable.

Fourth-generation MacBook Pro laptops, first released in October 2016, use USB-C for all data ports, and for charging. Windows laptops using USB-C ports for charging include some Acer Aspire, Asus Zenbook, Dell XPS, HP Sprectre and Lenovo ThinkPad models. Many other laptop models use an assortment of chargers, usually incompatible with everything else.

While the European Union has relied on consensus to standardize handheld device connections, this has not worked. While most manufacturers use USB-C connectors, Apple uses a Lightning connector. Now, the EU has said it will legislate compliance that will force all providers of handheld devices, including Apple, to use USB-C connectors. When implemented, this will probably have implications for the entire world.

USB connectors are at the heart of legacy-free computers, a term devised by Microsoft to describe a PC without a lot of the equipment previously found on beige boxes. Much of it large and slow. Most users appreciate this redesign, and especially the fact that a legacy-free PC must be able to boot (start up) from a USB device. The exception is that gamers, because of latency (time delay) issues, want to retain their PS/2 keyboard connectors.

Work on USB began in 1994, with a mandate from seven companies: Compaq, DEC, IBM, Intel, Microsoft, NEC, and Nortel. The goal was to replace a multitude of connectors with a single interface, and to increase data rates to and from external devices. A development team was established by Intel at Folsom, California led by Ajay Bhatt (1957 – ). The first integrated circuits supporting USB were produced by Intel in 1995.

The USB standard is currently maintained by the USB Implementers Forum (USB-IF), with four generations of specifications: USB 1.x (1996), USB 2.0 (2000), USB 3.x (2008, 2013, 2014, 2017) and USB4 (2019).

USB 1.0 ports are no longer relevant. However, efforts have been made to make all interfaces made after that backwards compatible. Thus, USB4 is backwards compatible with everything between USB 3.2 and USB 2.0.

ProtocolsUSB 2.0
USB 3.0
USB 3.1
USB 3.2
Data rate 480 Mbit/s5 Gbit/s10 Gbit/s20 Gbit/s40 Gbit/2
Type AOriginalBlueBlueNoNo
Type BOriginalBlueBlueNoNo
Type CYesYesYesYesYes

USB 1.0 from 1996-01 provided 12 Mbit/s of data transfer. When USB 2.0 was introduced, an unshielded cable version allowed for the attachment of inexpensive peripherals at a data rate of 1.5 Gbit/s.

USB Connectors

There are two versions of USB connectors one on a device and the other that fits into it on a cable. The device or female connector is referred to as a receptacle or port. The cable or male connector is referred to as a plug. Originally, a USB connection was always between a host or hub at the A connector end, and a device or hub’s upstream port at the B connector end. This is why peripherals, such as printers, use Type-B connectors. With handheld devices, the charger is regarded as the A end, while the device is regarded as the B end. Things are no longer so simple.

Port Type-A Type-B Mini Type-B Micro Type-B USB-C
Pins 4 to 9 4 to 9 4 to 9 4 to 9 24
Insertion/ removal cycles 1 500 1 500 5 000 10 000 10 000

The Future: USB4 & USB-C

The future of USB connectivity is the USB4 protocol and the USB-C connector. Yes, both of these could be replaced, and probably will be sometime in the future, but both represent reality now. While every USB-C port looks the same, they do not all provide the same functions. The main functions are data, video and power transfer. It is not possible to tell by looking at the port what is incorporated. If there is no documentation stating otherwise, consumers have to assume that they are simply data ports.

The USB-C connector began its use using the USB 3.1 protocol, which allows data transfers at 10 Gbps, theoretically twice as fast as USB 3.0. The USB 3.1 protocol can also be applied to USB 3.1 Type-A ports. Note: USB-IF has created unnecessary name confusion in that 3.0 connectors are also known as USB 3.1 Gen 1 & USB 3.2 Gen 1 x 1 while USB 3.1 connectors are also known as USB 3.1 Gen 2 & USB 3.2 Gen 2 x 1. The new USB 3.2 port was referred to as USB 3.2 Gen 2 x 2. The x 1 or x 2 refers to the number of lanes.

USB4 incorporates the Thunderbolt 3 protocol into the USB mainstream. The Thunderbolt interface was developed by Intel and Apple. It combines PCI Express and DisplayPort into two serial signals and provides DC power. Thunderbolt 1 and 2 use a Mini DisplayPort connector, whereas Thunderbolt 3 uses the USB-C connector.

USB Cables

Depending on phone, computer and vehicle configuration several different cable types may be required. In Scandinavia, Clas Ohlson stores offer a large selection, as do many specialist stores and online stores.

  • Android devices
    • USB-Micro B to USB-A: Connect older Android phones to older chargers, older computers, and older automobile data ports.
    • USB-C to USB-A: Connect newer Android phones & newer iPhones to older chargers, older computers and older automobile data ports.
    • USB-C to USB-C: Connect newer Android phones to USB-PD (power delivery) chargers, USB PD compatible batteries, some computers (with USB-C ports), 12V car chargers, newer automobile data ports.
  • Apple devices
    • Lightning to USB Type-A: Connect most iOS devices to legacy automobile data ports for CarPlay
    • Lightning to USB Type-C: Connect most iOS devices to current generation macOS devices using USB PD compatible batteries, wall chargers, and 12V car chargers.
  • Other
    • USB Type-A to proprietary cable/magnetic connector charger for Apple Watch or Samsung Galaxy Gear/Android Wear or older Apple Mac equipment.

Additional information on USB-C ports will be presented in the two next weblog posts in this series: 7. Video connectors (2020-02-18) and 8. Power supply/ charging (2020-02-25).

An Aside: PS/2 keyboards

First, a PS2 keyboard is not a PS/2 keyboard. The former refers to Sony’s Play Station 2, launched in 2000. The latter, to ports on IBMs third-generation personal computer, the Personal System/ 2, launched in 1987. It is an ancient and outdated system. Yet, gamers often prefer to use PS/ 2 keyboards (and sometimes even mice) for several reasons. First, PS/2 is analog. Whenever a button is pressed, it sends a command to the computer immediately. This contrast with USB, where the computer polls USB ports, and through them attached devices, at a rate dependent on the frequency of the port. Previously, this was about 125 Hz or so, which could introduce a latency (delay) from 0 to about 8 ms. Polling frequency on modern computers is about 1000 Hz, which reduces this latency to a maximum of 1 ms.

PS/2 keyboards also support N-Key rollover, which allows users to press as many keys as they want, simultaneously. This was not possible with USB keyboards, however many newer USB gaming keyboards support this now.

PS/2 peripherals work immediately without drivers. This is especially useful when diagnosing motherboard and related problems that USB devices cannot detect.

PS/2 devices are not hot-swappable. If a device is plugged into a PS/2 port when a computer is operating, the machine will have to be restarted for the device to function.

Unlike keyboards, USB mice have an adjustable polling rate, allowing them to have polling rates of up to 1000 Hz. Thus, they have had far fewer issues than USB keyboards.

PS/2 hardware is being phased out, and is unavailable on many modern gaming motherboards = a printed circuit board containing the main computer components along with various connectors. Unless that hardware is built into the motherboard, there is no point in using PS/2 equipment, and no point in using a USB adapter to correct any of USB’s deficiencies. At that point it is “game over” for PS/2, and the user might as well use USB peripherals.

Clouds & Puddles

Clouds are not always cute. Sometimes they are threatening, with the potential to damage, injure and even kill. Inderøy, Norway 2015-08-11. Photo: Patricia McLellan.

This weblog post is written to help people gain a better understanding of a house/ home/ residential computer network.

The Xample family with mother Ada, father Bob, cat Cat and daughter Deb are going to serve as an example. Currently, the family has the following equipment. Both Ada and Deb have iPhones, but Bob has a Samsung phone. In addition, Ada uses a Mac laptop, Bob has an old Acer desktop machine, while Deb uses a Chromebook laptop, that belongs to her school. The family is connected to the internet with a router, and they have an old Canon printer.

Some basic vocabulary

Sometimes, language can be confusing. To communicate about computers, people have to use words the same way, or misunderstandings will occur.

Users are people. Admittedly, there could be situations where something other than a human is a user. For example, at some point in the future Cat might be able to activate a feeding station. That would make Cat a user.

A computer, frequently known as a device, consists of hardware and software. Hardware is made up of physical/ mechanical components. Yet, these components will not work without software, a collection of instructions and associated data, that provide services.

Software capable of doing something is called a program. A computer program that is running/ working is usually referred to as a process. Software is written in a computing language that humans can read, and programmers can understand. This source code is then translated into machine code that the specific hardware on a machine can understand.

Operating systems are an important category of software. An operating system is the most fundamental program. It controls the functioning of the hardware and direct its operations. It manages the hardware including component parts, but hides the details from users. The Xample family, like most families, use several different operating systems. The iPhones use iOS, the Samsung phone uses Android, Ada’s Mac laptop uses macOS, Bob’s desktop uses Windows 7, Deb’s Chromebook laptop uses ChromeOS. Both the router and the printer also have their own special operating systems.


The term network can be used as either a noun or a verb. Begin with the verb, to network. This is a situation where two or more devices are able to exchange information with each other. The noun network refers to the sum of devices that are connected together. When networking, each connected device is referred to as a node. In the above case, an end node is connected to a network node, the iPhone and the router, respectively.

Nodes are connected to each other using data links. These links may be wired or wireless. The most common type of wired link is the Ethernet cable. The most common type of wireless link is WiFi. While some houses have only WiFi links, there can be good reasons for using cabled links if there is an opportunity for it.

Nodes don’t need to have a direct connection to each other, to be part of a network. Thus, one node could be located in Bergen, another in Detroit, and a third in New Westminster. This is an example of a wide area network (WAN). If the nodes are all located in the same cluster of buildings it is a local area network (LAN). For example, there could be several nodes inside a house, but one in a garage and another in a shed.

Computer professionals often use the terms client and server to describe a computing model. These are confusing terms. Fortunately, most people do not need to use them. The important thing to know is that a client either does local work or requests an external service. A server either provides that service directly to a client, or supervises an external supplier working on behalf of a client. Both terms can refer to either hardware or software. Focus on the software to understanding what is happening.

To help the Xample family transition to a network suitable for them, we are going to look at four challenges facing the family.

Challenge #1 Sending an email with an attachment

Ada has struggled for the past year to knit herself a sweater. It is finally finished, and she has taken a photo of it with the camera on her iPhone. She wants to send a copy of the photo to her brother Ely.

When Ada uses her phone to write an email, she is using an email client that is built into the iPhone. This client also allows her to attach the photo. When it comes time to send the email and its attachment, Ada uses an email server built into the iPhone that allows it to use the router to send out and receive emails.

In this example, there are two communicating devices, Ada’s iPhone and the family router. There is a network, even if it is small, simple and temporary. The two devices are connected using WiFi,

The router breaks both the email message and the photo into data packets. Each packet is equipped with a coded form of Ely’s email address. To find out where to send information, the router looks up an address using a routing table. If Ada receives an email from someone, the router will reassemble incoming data packets so that these can be understood. At home, most people use a digital subscriber line (DSL) or cable router connected to the Internet through an Internet service provider (ISP).

A DSL router typically integrates a modem. A modem sends packets of data across telephone lines, TV cables or optical fibers. A modem, by itself, does not provide the functions of a router.

Challenge #2 Printing

Ada wants to take a copy of the photo on her next visit to her grandmother Fay (1919 – ). Fay is not computer literate, but likes to decorate the walls of her room with photos. Before looking at what is happening in detail, we are going to learn a few more terms. To print a letter on paper, a print server will coordinate the printing process.

The main challenge with the family Canon printer is that it is so old that it doesn’t have any WiFi connection and won’t connect directly to the iPhone.

Ada connects her iPhone to her MacBook using the iPhone’s charger cable. She plugs the charging end into the iPhone, and the USB end into the MacBook. She then opens her Mac Photos app on her Mac laptop, clicks on Import, selects the photo she wants to transfer, clicks on Import (#) Selected, then finally clicks on Albums. Now the photo is on her laptop, and Ada can disconnect the charger cable.

To print the photo, Ada takes a USB cable, permanently attached to the printer, and plugs the other end into a USB port on her computer. Using a printer program and drivers, previously installed on her laptop, she can now print the photo. By plugging in the cable, Ada has once again set up a small, simple and temporary computer network. This time, it consists of the MacBook laptop and the Canon printer.

Challenge #3 A Permanent Network

Deb has her bedroom upstairs. If she wants to use the printer she has to take her Chromebook downstairs to attach it into the printer, using a USB cable. This is inconvenient. Most individuals/ couples/ families need system resources that can be shared by all/ many/ some users effortlessly. The basis for a permanent network may already be in place with the WiFi capabilities that are built into most domestic routers.

WiFi is a set of standards that allow devices to communicate with each other wirelessly. Devices that can use WiFi include desktops, laptops, smartphones, tablets, smart TVs, printers, digital audio players, digital cameras, cars and even drones.

Some families may consider replacing their printer with one that has WiFi capabilities. An alternative approach is to keep the printer, but to invest in a Network Attached Storage (NAS) server. A NAS can act as a print server, letting approved users print on a common printer.

Equally important, it can also act as a file server, so that common files can be stored in a central place and used by everyone. Such files include media files: video files, audio files, e-books; family photographs, and documents used by the entire family.

Everyone in the family will have to become users of the NAS, with their own log-in. Be sure to add an additional user, called Guest. Not all users are treated equally. Users have to log their client devices onto the system with a user name and a password, or some other approved form of identification. In this way, random visitors are prevented from accessing the server and its resources, without permission. Guest will typically be able to access the internet, but not able to access files on the NAS or use the printer.

A NAS can also backup personal files. These backups can be encrypted and password protected,so that they are unaccessible to others.

The Xample family decide that a QNAP TS-251A best suits their needs. They equip it with 4 TB of storage, which they regard as adequate for their needs. The printer can now be permanently connected to the NAS using a USB port, given access to users. Many printer drivers are instantly available, although older printers may require some effert to download appropriate drivers. If the printer is compatible with the NAS, it will display a message to confirm that the printer is connected.

Challenge #4 Clouds & Puddles

The Xample family now have 3 smartphones, 2 laptops, 1 old desktop, 1 printer, 1 router and 1 NAS. The NAS can function as a print server and a file server. It is also a media centre, serving videos and audio.

Computer hardware manufacturing companies are always keen to describe old products with new names. They are always looking at ways to make their rather dull equipment seem more important than it actually is. Edge and cloud computing are two such names.

An edge computer, in dataspeak, is a local server device at the edge of the internet, hence the term. Many will find it difficult to distinguish an edge computer from any other server, because almost everything today is connected to the Internet. However, in years past, many local servers were only connected to local devices using a local area network (LAN) typically wired with Ethernet cable. There was no connection to the outside world.

The cloud, in dataspeak, refers to someone else’s server. Companies that offer cloud services to the public often claim that they do the heavy lifting, storing and safeguarding data. This is not always the case. Sometimes they lose data. Sometimes they lend data to others. They might even keep a copy of it, when you ask to have it back. The misuse of data held in trust, may have economic as well as other consequences. Adobe, Amazon and many other companies are very keen for consumers to visit a nearby cloud, and use software as a service. This is the most profitable for them. Using a cloud can be expensive.

For a short period, just after cloud computing came into vogue, it became fashionable to name non-cloud servers after bodies of water. Large businesses might refer to their in-house servers as lakes. Referring to a server at home as a lake verges on the pretentious. Modesty dictates referring to smaller bodies of water: a personal (puddle) server, a nuclear family (pool) server or an extended family (pond) server.

Fun Assignment: The reader is asked to distinguish a carbon based error from a silicon based error. Assistance with this problem can be found here.

Devices Future

Volkswagen and D-Wave Systems have used quantum computing to find optimal routes, as illustrated here in Lisbon, Portugal, and available as an app near you. (Photo: Volkswagen)

… and the answer is, everywhere.

Now for the question, where do people want to use computing devices?


After trying to collect and interpret validated statistics, I have given up and present some numbers than might approach something meaningful and coherent. Some are based on information collected by Simon Kemp, dated 2019-01-31. Other bits come from Wikipedia, such as this article, along with a variety of other places with assorted dates.

With a world population of 7.7 billion people, there are over 5 billion handheld devices, the vast majority also referred to as mobile phones, increasingly smartphones, although they do much more than connect people using voice communication. It would be much more honest to eliminate any reference to phone in the description. The German Handy or the French Portable, are both better. Other devices in this category include tablets, and similar devices lacking keyboards. Regardless, Android operating system variants clearly and increasingly dominate, with at least 75% of market share, with Apple’s iOS declining market share taking most of the remainder. It remains to be seen if Huawei will be able to introduce a viable alternative to Android.

There are two important characteristics that distinguish handheld devices from larger personal computers. They are the large screen size and the use of a keyboard input device. Minor differences also include the use of a mouse or some other pointer, They are often referred to as laptop and desktop machines. In terms of the world, this is small segment of machines compared to mobile devices, with its importance decreasing. Part of the reason for this decline is their inability to be used everywhere.

There is general agreement that the billionth personal computer shipped in 2002, and that there were one billion such computers in operation in 2008. The dispute is how many are in use now. Some are looking for a magic number of 2 billion, but 1.5 billion units is far more likely. Windows will be installed on at least 75% of machines, MacOS on, say, 13% (which to me seems high), ChromeOS on 6% (at least in the US, and higher than I experience in Norway) and Linux on 2%. The 2019 Stack Overflow developer survey gives very different figures on what is found on machines used by computing professionals. In round numbers: Windows on 45%, MacOS on 30%, and Linux on 25%.

Another category of computer is the embedded device. One essential aspect of these is the electronic control unit (ECU). Domotics refers to home robotics. It includes all aspects of smart home technology, including sensors that monitor the environment and actuators that activate controls. These include temperature, lighting and security. However, it is pervasive, found everywhere from electric toothbrushes, to toasters and every other form of kitchen machine. Today, even a lightbulb can be considered an ECU. A typical smarthouse may contain hundreds of these devices.

The vast number of ECUs expected, plus its vulnerability in terms of security, means that WiFi can only be a temporary solution. While communication can be built on top of 120/240 V AC circuits, most devices, including LED lights, actually use low voltage DC power. Anyone building something new should be installing Ethernet cable 6A at a minimum, with connections to every room. Power over Ethernet, (PoE) can then provide DC power to almost everything needed.

I expect clothing will soon include embedded devices, so that personal data can be continuously collected and monitored. In Sweden, I note that several individuals have voluntarily inserted RFID devices into their bodies, so that they can use these to identify themselves, rather than relying on PIN codes. Unfortunately, it is probably only a matter of time before these devices become mandatory.

Embedded devices are also found in cars where even the most primitive contain 25 – 35 ECUs. More luxurious models may have 70 or more ECUs. Hopefully, autonomous vehicles will soon be on streets near you. The last thing this world needs is a nut behind the wheel, especially one that feels provoked into road rage at the slightest offence. Electric vehicles are already here, with Tesla’s innovations leading the way. In Norway, there will be no opportunity for people to buy fossil fueled vehicles (including hybrids) after 2024. Everything will probably be battery electric, as an explosion at a hydrogen fueling station has dimmed everyone’s interest.

Command and control (C2) is defined by Marius Vassiliou, David S. Alberts and Jonathan R. Agre in C2 Re-Envisioned: the Future of the Enterprise (2015) as a “set of organizational and technical attributes and processes … [that] employs human, physical, and information resources to solve problems and accomplish missions.” (p. 1) This definition can apply to individuals, households, organizations, small businesses, large enterprises or even the military. One major challenge has been the tendency of large manufacturers of ECUs to consider just their own product range, and to make controllers for these and only these. This is not a viable solution. Our household has opted for the most inclusive solution, found in Home Assistant.

Miniaturization will continue into the future. I am uncertain about the future form factor of personal devices/ phones. Asked if they will shrink to wristwatch size or remain about the size they are today? Today’s form factor wins. Yes, one can imagine screen technology being built into glasses, or wrist watches, but will it happen? It will be interesting to see what has happened in 2040 and beyond.

In terms of PCs, they could be doomed to extinction. Physically smaller personal devices will be capable of doing everything PCs do. However, there may be situations where a person may want a larger screen, a keyboard and a pointing device. So the personal device will have to interact with these. I am not certain when voice control will replace the keyboard. When I first studied computing, in the mid-1970s, 1980 was even considered a target date for its replacement. However, that was based on people going from card punches to something else.

In terms of servers, one can also envisage a household having something the size of a small media centre, perhaps 100 x 100 x 50 mm (4″ x 4″ x 2″) which is about the size of our Asus PN 40 media player. At the current rate of miniaturization, it should be able to hold at least 100 TB by 2040. One could ask why anyone would need so much storage capacity, but today everyone seems capable of using every last byte of storage they have, and I see no reason for attitudes to change. Computers will be used in new areas because people have the processing power and data storage capacity to do it.

Perhaps the greatest change will come as quantum computing matures. Quantum computing is real. It allows computations to be made in seconds that would take a conventional supercomputer considerably longer. Google claims that its Sycamore processor with 54 Qubits, has achieved quantum supremacy, and is the most advanced quantum computing processor in the world, capable of processing in 200 s, what a Summit supercomputer would use 10 000 years to accomplish, making quantum computing 1 577 880 000 times faster. IBM has countered this, stating that it would only take 2.5 days, making quantum computing about 1 000 times faster. Regardless, quantum computing will provide faster calculations.

With my origins in Vancouver/ New Westminster, and with some of my most positive learning experiences at the British Columbia Institute of Technology, I will end this post by mentioning its Burnaby neighbour, D-Wave systems. They announced in 2019 their next-generation Pegasus quantum processor chip, the world’s most connected commercial quantum system, with 15 connections per qubit, and with more than 5000 qubits, to be available in mid-2020.