Gary Kildall: A tidbit

This is an Amstrad NC200 notebook computer from 1993, with a Z80 processor, 128kB of RAM and a 16MB CF card being used as a flash drive. It is running an open source CP/M distribution. Photo from Hjalfi, 2020.

Originally, this post was started to commemorate the release of the first operating system for microprocessors, CP/M. My best guess for its release date is 1974-04-25. Many sources state april, but are hesitant to specify the exact date. The person responsible for its development was Gary Kildall (1942 – 1994). This weblog post is published on the thirtieth anniversary of Kildall’s death, rather than the 50th anniversary of the first CP/M release.

Kildall has his origins in Seattle, Washington. His grandfather was a Norwegian immigrant, who ran a navigation school. Kildal is the name of a farm at Hægeland, Vest-Agder, in the south of Norway. His maternal ancestors had their roots in Långbäck, Skellefteå, Sweden before his maternal grandmother Sophia Lundmark emigrated to Edmonton, Alberta, Canada. His mother then immigrated to Seattle.

Kildall was awarded a doctorate in computer science from the University of Washington in 1972. He then worked as a computer science instructor at the at the Naval Postgraduate School in Monterey, California. This was to fulfill his military conscription obligations, since the US was still engaged in the Vietnam war.

Later that year, to learn more about processors, Kildall bought an Intel 4004 processor and began writing experimental programs for it. Intel lent him 8008 and 8080 processor systems. In 1973, Kildall developed the first high-level programming language for microprocessors, called PL/M = Programming language for microcomputers. It incorporated ideas from: PL/I = Programming language one, developed at IBM starting in 1964; ALGOL = Algorithmic language, originally from 1958; and XPL = expert’s programming language, from 1967.

One of the first software projects Kildall worked on, with Ben Cooper, was the Astrology Machine. It is generally regarded as unsuccessful, but gave Kildall an opportunity to field test programs he had written: a debugger, an assembler, part of an editor, and a Basic interpreter that he used to program.

In 1974, Kildall developed CP/M = Control Program/Monitor (originally)/ Control Program for Microcomputers (later). Intergalactic Digital Research (originally) /Digital Research, Inc. (DRI, later) was established by Kildall and his wife Dorothy McEwen (1943 – 2005) to market CP/M.

In 1975, Kildall developed a set of BIOS = Basic input/ output system routines, firmware used to provide runtime services for operating systems and programs and to perform hardware initialization during the boot process = power-on startup. BIOS initially allowed 8080 and compatible microprocessor-based computers to run the same operating system on any new hardware with trivial modifications. Later different BIOS applications were made for other computer families.

A source-to-source translator = source-to-source compiler (S2S compiler) = transcompiler = transpiler, is a type of translator that takes the source code of a program written in a programming language as its input and produces an equivalent source code in the same or a different programming language. In 1981, DRI introduced one of these, calling it a binary recompiler. XLT86 was written by Kildall. It translated .ASM source code for the Intel 8080 processor (in a format compatible with ASM, MAC or RMAC assemblers) into .A86 source code for the 8086 (compatible with ASM86).

Kildal initiated the creation of the first diskette track buffering schemes, read-ahead algorithms, file directory caches, and RAM drive emulators.

At this point it becomes difficult to separate Kildall’s role as innovator/ inventor and that as initiator/ project manager/ executive, where other engineers at DRI and elsewhere made significant technical contributions.

For example, Tom Rolander made most of the developmental inputs to CP/M starting in 1979, that later resulting in these operating systems added preemptive multitasking and windowing capabilities as well as menu-driven user interfaces. These are found on: Multi-Programming Monitor Control Program (MP/M), Concurrent CP/M, Concurrent DOS and DOS Plus.

In 1984, DRI started development Graphics Environment Manager (GEM), known primarily as the native graphical user interface of the Atari ST series of computers, providing a desktop with windows, icons, menus and pointers (WIMP). This was an outgrowth of a more general-purpose graphics library known as Graphics System Extension (GSX), written by a team led by Don Heiskell since about 1982. Another major contributor was Lee Jay Lorenzen at Graphic Software Systems.

Kildall and Rolander founded Activenture in 1984. They created the first computer interface for video disks to allow automatic nonlinear playback, presaging today’s interactive multimedia. This company became KnowledgeSet in 1985, which developed the file system and data structures for the first consumer CD-ROM, an encyclopedia for Grolier.

3 Replies to “Gary Kildall: A tidbit”

  1. Brock. Thanks for collating these facts and info. I have often wondered about CP/M but never enough to investigate myself, I’ve allways ended up looking at something less obtuse or of more immediate interest. For instance how to make oatcakes!!!!! The ones with some Cheddar cheese added.
    Or how to explain ‘getting an antenne to work’, to the new students.

  2. Cheddar. In my childhood, in British Columbia, there was only one type of cheese, so that in my mind cheese and Cheddar are synonyms. After we moved to Norway, at some time we were able to buy imported English Cheddar at our local Coop. Now a bland, barely edible Norwegian substitute has replaced it. After a initial purchase, and despite the label, we have had to give it up. Tomorrow, LB6HI and I (LB2XJ) are heading off to England (Portsmouth and Isle of Wight) then on to Newfoundland for two weeks. I am looking forward to buying some real Cheddar cheese while away, and even taking some home to an equally deprived Trish, who will not be travelling with us.

    1. Just checked the import rules for Norway. I will not be allowed to import Cheddar cheese from the United Kingdom.

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