Message-ID: <>
Date: Fri, 26 Jun 2009 17:38:19 -0400
From: Herb Johnson 
Subject: Response to Werner's English CP/M pages

I saw your recent post in USenet comp.os.cpm, and so I looked at
your CP/M Web pages. I;m in the USA and an English speaker so:

Your pages look very reasonable to me, thanks for your efforts to 
support CP/M.

I have a few minor corrections to make, to your CP/M history. They
are small corrections, but I'm familiar with the history. You are
welcome to look at the history I've put together on my Web site,

All my reference information is noted, you can review the
references yourself, they are fun to read. Most of the references
are from Kildall himself, or from accounts of people Kildall
worked with. So I think I have a correct and verifiable history.

Your page says:

 From Operating System Documentation Project: Gary A. Kildall
developed for the company Intel the PL/M programming language for
the Intel 8008, derived of PL/I in 1973. In the same year he
developed the operating system CP/M (Control Program for
Microprocessors) in PL/M. It was the first operating system for
Intel based computers. Kildall set up with his wife Dorothy McEwen
the company DR Inc. (Digital Research Incorporation) in 1976. At
first CP/M was designed by DR only as a pure file manager program
for 8-bit x86 computer and sold by Intel. In 1976 there was a CP/M
Bios for Intel 8080 computers. At this time CP/M was the dominating
operating system on the market and used by the most computer
manufacturers on theyre computers to. In 1981 dozens of computer
machine types competed under various operating systems like CP/M in
numerous variations. Additional there were proprietary operating 
systems and UNIX variations. CP/M was used in 1985 worldwide 
approximately 4 million times in different versions. CP/M was
renamed to DR-DOS after few other releases in 1988.


Kildall began some CP/M development in 1973, but it was not 
completed and running on actual hardware until "the fall of 1974",
as he wrote himself in a Dr. Dobb's Journal article. The first 
copies of CP/M sold were likely sold in late 1974 or early 1975, 
but Kildall says he first licensed CP/M in 1975. John Torode, his
colleague who worked on Kildall's floppy controller, sold CP/M to 
the public before Kildall, in 1975.

CP/M was NOT the "first operating system for Intel based computers". 
That is too general a claim. Companies which sold floppy-disk 
controllers and drives, offered 8080 compatible floppy-disk based 
operating systems with their products before 1975 or earlier. Check 
this Web page of mine about those:

And Intel offered ROM monitor and paper tape operating software for 
their 8080 and 8008 processors, as part of their Intellec 
development systems, before 1975.

It is fair to say that CP/M was an early and dominant, or
predominant, floppy disk operating system for processors compatible
with the Intel 8080. The reference you quote does says that as well.

Your page says "CP/ sold by Intel". Intel did not offer 
CP/M, to my knowledge. They offered ISIS, a developmental operating
system, some time after DRI's CP/M. later they offered other 
Intel-developed OS's.

Your reference says "In 1981 dozens of computer machine types 
competed under various operating systems like CP/M in numerous 
variations." I think the English you wanted to use would be more
like this. "In 1981 dozens of companies provided CP/M-like 
operating systems which competed with CP/M." Some companies wrote
their own version of CP/M, to avoid license fees. Some of those 
companies, like Cromemco, was told by Digital Research to buy a
license or face legal action. Cromemco bought a license.

There were HUNDREDS of companies which produced S-100 based systems 
by 1981 - I have a list of them on my Web site. Plus, of course, 
companies which produced non-S-100 Z80 computers like Osborne, 
Kaypro, etc.

"CP/M was renamed to DR-DOS" is not accurate. A better English 
statement would be, that Digital Research developed OS products 
after CP/M, such as Concurrent DOS and DR-DOS. YOu can read about 
the 1980's and 1990's history of DRI, and of their products, on my
Web pages. Today, DR-DOS and CP/M are owned by DRDOS.COM, a US 
corporation. YOu can still buy DR-DOS from them today, and they 
permit CP/M to be offered for personal use at no charge.

I hope these details and comments are useful and informative to you. 
It's not important that your Web site has every detail correct about 
CP/M history. The most important thing is that you continue to help
and inform people about CP/M and programming of 1970's Intel-based 
computers. Thanks again for your Web site. With your permission, 
I'll add a Web link to it from my page of Web links at

YOu are welcome to link to my DRI Web pages, please use THIS Web 
link if you do:

Herb Johnson

Herbert R. Johnson, phone 609-771-1417, New Jersey USA   retro-technology home pages
-- S-100, CP/M history by "Dr. S-100"
-- other old tech in iron, glass, rock
domain mirror:
email: hjohnson AAT retrotechnology DOTT com
if no reply, try: herbjohnson ATT retrotechnology DOTT info