MS-DOS was *not* an illegal clone of CP/M

[liam_on_linux]

"MS-DOS" is the MS version of what IBM sold as PC DOS. Microsoft produced that on very short notice by licensing (note, not buying) 86-DOS from Seattle Computer Products. That was originally called QDOS, for Quick’n’Dirty OS.

Tim Paterson wrote QDOS based on studying the docs for CP/M and CP/M-86. It was API compatible, but used a different disk filesystem: Paterson used the FAT format of MS’ standalone disk BASIC.

It was wholly-new code, but written to be closely compatible with DR’s published info about CP/M.

That is not even reverse-engineering. Indeed CP/M-86 was released late and it didn’t even exist to be reverse-engineered yet, AFAIK. QDOS was written for and sold with SCP’s 8086 cards in 1979; CP/M-86 did not ship until 1981.

Writing compatible code to a published API is what APIs are for. That’s why the info is published.

QDOS wasn’t a clone of CP/M-86; in fact, it is older than and predated CP/M-86.

It was a compatible OS written to info DR published. That is entirely legal. DR published the APIs intending this for app writers, not for people writing OSes compatible with DR OSes, but it’s not breaking any rules.

In fact in the late 1970s there were lots of CP/M clones out there, such as CPN and Cromemco CDOS and many others. Later MSX-DOS was a much-enhanced CP/M clone.

The difference is, most other companies cloned CP/M on 8080 or Z80. SCP did it on 8088/8086.

But while yes, it’s arguably something like a clone (for different hardware, with a different file system), it was just one of many and didn’t use anything illegal or violate any licenses.

The key thing is that QDOS ran on then-modern hardware with a future. Most of the others ran on what was rapidly becoming obsolete hardware. SCP QDOS became 86-DOS became PC DOS and MS-DOS, and sold in the tens of millions of copies, and made MS huge amounts of money.

DR and IBM made big bad mistakes and it cost them dominance of their industries and lots of money. MS was smart and got lucky and got very very rich.

Later on, MS abused that power repeatedly, stole code, copied ideas, unfairly pushed rivals out of business, and generally became a bully and a criminal. MS effectively killed Be, Netscape, and Central Point Software; it crippled Aldus and STAC; and many more.

But DR survived and briefly it staged a successful comeback, before being bought by Novell.

I entirely understand how angry Dr Gary Kildall was. It was justified. But he did make mistakes. Sadly some of them are only clear in hindsight. DR should have rushed to make CP/M-86 quickly for IBM, and reserved the rights to sell it to others, as Microsoft did. DR should have sold single-user single-tasking CP/M-86 cheaply, building the market, and made Concurrent CP/M the premium product. It should have sold GEM cheaply to get wide adoption. It should have made standalone single-user multitasking CP/M a desirable power-user OS, rather than aiming at the multiuser market, which was on the way out as PCs got cheaper and cheaper.

But as little as I personally like MS, in how it cornered the market and became rich, it did it by being clever, and fast, and outmaneuvering bigger, slower rivals, and there’s nothing wrong with that.

Comments

[history_monk]

You've never done any GEM programming, have you? When you use the GEM desktop, you're using almost all of GEM's capabilities. It's really quite remarkable how little is there, and it isn't at all surprising that the few successful GEM-based applications (notably the early versions of Ventura Publisher) came with their own extended versions of GEM.

The world is actually better off with Windows as a dominant GUI than it would have been with GEM. It would be better yet had it been X11, but you can't have everything.