30 years of CP/M

First presented June 10th 2007 at Vintage Computer Festival East 4.0 at Infoage, titled "30 years of CP/M", by Herb Johnson. Also presented at University of Deleware / Newark in Oct 14 2007 for course on computer history and restoration. Most recent revision of this expanded version is Feb 03 2009, some fixes in June 2011. - Herb Johnson

Overview: We make the case that the work of Gary Kildall and his colleagues and clients in the early 1970's, produced an operating system (CP/M) and a collection of software tools which set THE STANDARD for subsequent personal computing. This standard, with other standards such as the S-100 bus, BASIC, video display and floppy drives, provided uniform technology for the foundation of the early personal computing marketplace. These standards enabling individuals and small companies to become productive and successful, using well-known and portable technologies. This market base supported the later entry of major companies like IBM who nonetheless had to provide products consistent with these standards and software products.

This presentation only covers the origins and development of CP/M-80 in the 1970's, but references past and later activity. Many individuals named, including Kildall and Torode, have not recieved the attention they deserve for this early and essential work. Original publications and first-person references are available to date key events, companies and products.

Contents (c) Herb Johnson 2008, referenced works copyrights by respective sources and authors. More information is available on my Web site for early Digital Research CP/M products and development at the link below, which references other Web pages and documents at my CP/M home page.

Related history of specific products and developments:

...on IMSAI is available on my IMSAI Web page

...of John Torode's Digital Systems and the first S-100 and CP/M floppy product is on its own Web page

...of Gary Kildall's Digital Research and the first CP/M, is on its own Web page.

...of floppy controllers for Torode's Digital Systems, IMSAI and Kildall, MITS's Altair, and iCom is on its own Web page.

...of the world of S-100 systems, my collection of S-100 documents and information on its own home Web page.

Learn more about my Retrotechnology.com Web site and technology history from linkes on my domain home page. Contact me from my business inquiry page.

Herb Johnson


I. The "digital" world of 1970 - computers very remote, large, expensive, rare

		Mainframes: IBM and PL/I. Expensive, rare
		Timesharing and the PDP-10: 
			FORTRAN and tools. not cheap, rare
		minicomputers: control, data collection. $50K a bargain
		accountants, engineers, scientists only
	information technology barely "digital"
		paper-based: books, magazines, newspapers; 
		punchcards, papertape, index cards

II. Digital electronics of early 70's, Kildall and colleagues

	early 70's digital world
		digital logic chips, hundreds per system
		IMS Associates, MITS in 1973: digital design
		DEC: "flip chip" logical design in hardware
		beginnings of microprocessors: Intel's 4004, 8008
			logic replacements for mechanical controls	
		1971: IBM "flexible disk" microprogram loader - the floppy disk drive
			for use in minicomputers by 1973 (Computer Design June '73)
	Kildall et al, microprocessors, design, and CP/M in the early 70's:
		limited function processors 4004 in 71, 72
		John Torode: '72 PhD at Univ of Wash
		Theodore Kehl: '61 Ph.D, joins U of W in late '60's. "mentor" of Torode		
		Kildall as student at Univ of Wash
			'71: writes XPL compiler for Algol on Burroughs m/f
				"heathkit" article on modular approach, standard tools
			PhD in May 72, XPL and ALgol compilation
				value of high level languages
		Kildall as faculty member, Naval School in '72
			starts MAA for consulting work at Intel
			uses 8008 as logic replacments using PL/M
			tools for editing files, debugging programs
			PL/M: via XPL, from Algol and PL/I
			paper tape editor

III. mid-1970's: microprocessor advance, Kildall moves to 8080 with more native tools

		Intel SiM-08 single board as breakthrough
			Claude Kagan's Home Reckoner article predicts personal computing
		Mar: Electronics article, "Microcomputers muscle in"
			processors as logic controllers
			Intel, Fairchild, National, Rockwell
		Kildall works on (8008?) Computer Cast horoscope machine
			a test bed for native development tools
		Kildall works for Intel:
			Kildall wrote Intel's PL/M 08, released June 1973 (see Wescon '74 article)
			8008 cross assemblers, cross compiler
			receives Intel Intellec 8 (8008)
			Intel's 8080 announced, Kildall upgrades 8008 tools
		Shugart floppy diskette drive, first CP/M coding
			"to support a resident PL/M compiler", does floppy controller design
		Nov: Torode & Kehl wrote logic machine modular design system
			published one year later in IEEE Trans. on Computers
			microprogrammed computer general design for specific uses
		Kildall pitches CP/M to Intel: no deal

	1974: Kildall gets 8080 upgrade to Intellec 8/80: PL/M for 8080, works on CP/M
		Feb: Kildall writes article on PL/M 80 for Wescon '74
		June: Kildall develops and publishes about 8080 application for (water) diving project 		
		July: Jon Titus and Mark-8 8008 system on Radio Electronics cover
		NCC '74: floppy controller how-to
		Aug: Kehl, Moss, Dunkel: automated digital design
		Sept: disk OS and floppy controller from ICOM 
			also see this iCOM Web page
		Kildall and Torode at work "in the fall of 1974"
			Kildall says Torode "completed his controller"; Torode says he "replaced" Kildall's controller. 
			Kildall's disk operating system "completed by 1974"
			see discussion on this Web page
		Kildall NCC '75 checkpoint paper: 
			page 99
			page 102
			8080 board
			CP/M system?
		late 74: MITS' Ed Roberts gets deal on 8080's, designs Altair 8800

	1975-76: what was expected market for microprocessors? not much compared to TV's.
		Jan 8 1976 report by Electronics Magazine:
			USA Consumer electronics market was/would be
			$7B in 1974, $6.5B in 1975, $7.5B in 1976, $10B in 1979
			about 50% TV's, 30% audio, 15% other consumer items
			$1B to $2B in integrated circuits,  microprocs $45M in 1974 to $500M in 1979!
			Microcomputers? 20M in 1974 to $500M in 1979
				in a data processing market of $17B in 1974 to est. $27B in 1979
				minicomputers (<$50K) alone: $600M in '74 to $1.1B in '79
				data terminals: $900M in '74 to $1.6B in '79

IV. 1975 and it all breaks loose
	1975: the early tools and products are developed

		Jan 75: Popular Electronics, MITS Altair 8800 cover
		early '75: IMSAI wants Altairs for hypercube, no deal
			Joe Killian decides to design similar unit 
			advertized IMSAI 8080 in summer '75 Popular Electronics
			developed, shipped in Dec - $400
            Mar 5 75: first meeting of Homebrew Computer Club in California
			several S-100 developers-to-be were members
		Kildall adds to OS an editor, assembler, debugger
			Intel turns down Kildall's offer of CP/M
			Torode's Digital Systems licenses CP/M to LLNL and Omron
                  Kildall and wife found Digital Research to develop and sell CP/M		
		NCC '75: Kildall "microprocs as logic elements" under PL/M
		late '75: Gordon Eubanks completes BASIC-E compiler
                  as MS thesis under Dr. Kildall; releases use to general public
		late '75: Torode's Digital Systems floppy controller w/ "CP/M" for Altair
			which uses a microcontroller design
			compare to 1973 Torode/Kehl design
                  see for Torode's Digital Systems products
		Multibus and ISIS from Intel for 8080
			8080 assembler "written in PL/M"
			only runs on Intel system, possibly only Multibus
			development only, not an application OS
		see the "race" for floppy controllers in 1975-76

	1976: microprocessors advance, things get cheaper including floppy drives

		many kinds of microprocessors available: 
			see this list of 36!
			prices drop, for instance on the 6800 in April
			Zilog offers Z80 processor in Jan article
		more disk OS's and floppy controllers: 
                  MITS Mar 76 announcement, 
				floppy controller with disk BASIC.
                  ICOM Jan 1976 ad, 
				iCOM developes S-100 floppy subsystem with FDOS by Sept 76, 
				check this iCOM Web page for evidence
			Nov?: Persci 1070 "intelligent diskette drive controller"
				serial interface for ASCII disk OS commands, I/O interface for data.
			Sykes floppy ad for Feb 1976
			June: Kehl, Dunkel; simplified floppy contrl design
				summary here
			CDOS written by Cromemco when no CP/M help given
		more cross compilers for PL/I-like languages
			Feb: Motorola's MP/L for 6800
			April: Intermetrics PL/M 6800 
			June: signetics PL/M+ for 2650
				also: MCT cross-assemblers, 6800 & F8 boards 
			National PL/M+ for PACE, IMP-16 (1975)
		more 8080 systems
			Intel's ISIS and Multibus 8080 cards & systems
			 The Digital Group (multiple procs) see my Web page on this
		more plug-compatible cards for systems
			Feb: MITS offers Altair, (Microsoft) BASIC, I/O cards  in ham magazine ad
				8800  at $439 kit $621 assembled
				4K DRAM board $195 kit $295 asmbld
				serial or parallel I/O board $115 kit $144 asmbled
				4K BASIC $60 and up
			more "Altair/IMSAI compatible" products from others
			June: IMSAI prices rise, floppy controller announced in ad
		other processors: 			
			Mos Tech 6501, 6502 in Oct 1975
			June: SWTP 6800 system SS-50 bus
			feb: KIM-1 offered
		minicomputers fight back: cheaper, more software
			typical ad by DEC for LSI-11

V. CP/M in early use

	1976 as word gets out
		April DDJ: "First Word on a floppy-disc operating system" by Jim Warren
			Digital Research, CP/M by name; products already a year old
			ED, PIP, CCP commands by name
			$70 for CP/M, controller $100-$350, drives $550-$650
		Aug DDJ: "The time for Floppy's is Just About NOW!" by Jim Warren
			Torode's Digital Systems floppy controller w/CP/M "available"
		Personal Computing '76 and the S-100 name alledgely appears
		late 1976: CP/M V1.3 for IMSAI by Kildall and Glen Ewing
			1st gen IFM/FIB floppy cntrl w/8080 proc
			seperate BIOS emerges
		Nov/Dec DDJ:  "Upgraded CP/M floppy disc operating system now available"
			purchased by Robert Swartz in late 75 - early 76 "no trouble with it"

	**CP/M as a product**: the CP/M ad in December 1976 BYTE magazine
		DRI's CP/M ad: w/ essential features: 
		complete: an OS, editor, assembler, debugger, batch
		adaptable: to any 8080 system with diskette drive, *by the user*
		mature: almost two years field use
		cheap: $70 per system, with docs

	1977 and CP/M products
		**CP/M hardware and S-100 support** Jan BYTE: 
			Torode's Altair/IMSAI floppy controller with CP/M 
			$1595 as 2-card set
		third CP/M license **sold to IMSAI** for IMDOS & 2nd gen cntrl DIO/PDS
		MITS sold to Pertec, expands product line
		July 1977: Date on Digital Systems (Torode) version 1.4 S-100 interface schematics to his floppy controller

		1978 S-100 Inc. catalog includes Digital Systems floppy controller
		Feb: IMDOS 2.02,  IMDOS 2.05 by IMSAI
		CP/M 1.4 in general release and for Cromemco, other companies
		Feb: Eubanks' Complier Systems and IMSAI offer CBASIC product.
			IMSAI pays Gordon Eubanks to write CBASIC for license to distribute it.

	CP/M 1.4 of 1978 - a complete product
		fundamental tools: OS of BDOS, CCP, BIOS, tools of assembler, editor, debugger
		CP/M 1.4 documents:
			intro to features & facilities" cover CCP and tools
			interface covers programming from PL/M view
			(interface contents)
			ASM, DDT, ED books

VI. 1978-79: CP/M refined and in larger release

	1979: Kildall's DDJ article "The Evolution of an Industry: One Person's Viewpoint". (pub. Jan 1980)
			Kildall reviews his earliest work on CP/M through IMSAI and version 1.3.
 		major revision CP/M 2.0 available: more disk features from BDOS into BIOS
		minor revision fix 2.2, became next generally available DRI product 

	CP/M 2.2:
		"intro" not greatly changed
		"interface" expanded BDOS call descriptions
		new "Users Guide": enhancements, BIOS descriptions, diskdef's
		new Alteration Guide to build new BIOS, gen it, BIOS source
		NO PL/M CODE discussed, assembler examples only

VII. Microcomputing in the late 1970's: general "personal" and business computers

	more powerful microprocessor systems
		more storage, more speed, more memory
		resident compilers/interpreters including BASIC, C, Pascal
		programs for non-programmers: word processing, spreadsheet, etc.
		move from multi-board to single-board computers 
		CP/M & floppies
		Z80 & S-100 bus
		CBASIC and Microsoft BASIC
		...yet other standards, other processors
	spread of technology from the bottom up, not yet top-down
		disk libraries
		clubs, newsletters, magazines
		BBS and dial-in systems
		hobby and engineering, to business and personal

VIII. CP/M development after CP/M 2.2 and after the IBM PC

	1980: DRI's MP/M for 8080 introduced.

	June 1981: Kildall's BYTE  article: "CP/M: A Family of 8-and 16-Bit Operating Systems"
		history of PL/M and early CP/M
		CP/M, MP/M CP/NET, native PL/I - all 8080
		CP/M-86, MP/M-86 mentioned in passing by DRI
		Kildall says 16-bit processors "already outmoded"

	1981: DRI buys Eubanks' Compiler Systems and CBASIC

	August 12 1981: IBM press release for the 5150 "IBM PC"
		$4400 with OS, two floppies, video monitor: not cheap
		OS, software, features all derived from current technology
		documentation like any other microcomputer of 1981
		open software sources, like any other microcomputer of 1981
		Kildall's DRI fails to reach terms with IBM
		Microsoft "PC-DOS" based on Seattle Computer Systems OS, largely CP/M-80 in design
			disagree? tell it to the court!
		BASIC a long standing product from Microsoft

IX. Summary: CP/M and DRI evolutionary history

	Kildall as developer and teacher, using mainframe-based tools
		asssembler and PL/M as tool set for Intel 8008, 8080
		native 8080 assembler, editor, debugger developed in PL/M
		OS developed to run the tools on floppy drives
		OS honed on early IMSAI

	CP/M 1.4 as fundamental tools, 
		some resident on 8080, some in PL/M
		limited ability to handle disk formats, embedded in BDOS

	CP/M 2.2 as a general-purpose, all-native OS development system
		no PL/M needed, no OS source needed
		handles multiple disk formats in BIOS
	1970's later products with more power for more hardware
		CP/M 3.0, MP/M for 8080, 
		GSX  for graphics, CP/NET  for networking & for slave CPU's
		C and PL/I languages

		Torode's Digital Microsystems develops Z80, 8086 systems, Hinet local network
			ultimately sold to Apricot Computers in the UK for networking 
		8086 versions for IBM PC and PC compatibles
		task switching and windowed products, 286/386 support

		1991: DRI sold to Novell Inc. for $120 millon.
		see  Business Week article of Oct 25, 2004
		later sold to Caldera, who later buys SCO.
	late 1990's: Caldera CEO Brian Sparks licenses CP/M to Tim Olmstead 
			archive of early CP/M for personal use
			collects code and docs, offers freely on the Web 

	21st century:
		Sept 2001: Olmstead developes archive. Died 9/11/01 of cancer
		Oct 2001; Lineo CEO Brian Sparks licenses Gaby Chaudry
			"unofficial CP/M Web site" maintains archive, adds more
            DrDOS Inc. (Sparks) buys all DRI rights.
		2006-07: Udo Munk revives CP/M emulator Z80PACK, verifies CP/M sources
			wraps early CP/M, 1.4, 2.0 with ISIS tools, PL/M

X. Where are they today?

	Gary Kildall & CP/M
		CP/M properties eventually sold to DRDOS Inc., active to this day
		Kildall died in 1994
	John Torode
		Digital Microsystems Inc in 1979, 
			developed Hinet local area network, sold DMS in 1986
		co-founded IC Designs with Theodore Kehl
		IC Designs merged with Cypress Semiconductor, Torode on Board
		both Torode and Kehl distinguished alums of U of W
	Al Shugart
		Shugart Associates, then Seagate. 
		w/ Seagate until 1999, Al Shugart died Dec 2006
	Gordon Eubanks: see this link
		co-developes Q&A database product; financed to run Symmantic which sells it
		Symmantic does well, acquires Peter Norton, Central Point. Major company in 2007.
		MITS bought by Pertec in 1977; last production mid-78
		Dr. Ed Roberts becomes an M.D. in private practice, then retires
		Pertec may have lasted through early 90's?
		Altair originals, replicas, emulators available
		Bill Millard founded Computerland, strange tales ensue
		1979 IMSAI bankrupcy sale: inventory to Fulcrum, WW Component; products to Fischer-Freitas 
		since 2001 imsai.net by Todd Fischer
			originals, emulators and major revisions of products available
		ended support for ISIS, MDS in 1993? (Hitex)
		sold Multibus to Radisys in 1999, to UST in 2001
		ownership of s/w not clear
		iRMX supported by Tenasys
		emulation for ISIS, MDS support from Hitex Ltd.
		ISIS emulator for MS-DOS as somethingware
		some deal in 1981 with IBM - ???
		still in business
		Gates retires in 2008

Contact information:

Herb Johnson
New Jersey, USA
To email @ me, see see my ordering Web page.

Copyright © 2011 Herb Johnson