Bottom line: there is no controversy. It was resolved many years ago. The article referenced, is simply a code-analysis product developer, showing off their product at an August 2016 conference. The article writer, shows no informed knowledge of the subject. The rest of this post, reviews the context of the referenced article, the un-controversial subject is resolved, and the promotional nature of the developer's efforts is laid out- all matters of my opinion but I'm informed and I make those cases. If this matter is not important to the reader, you can stop here, my apologies for the length remaining. I have some early CP/M information and references to CP/M related litigation on this Web page, with links to other pages. Thus my interest in the subject. My Web pages were recognized by an IEEE biographer of Gary Kildall when IEEE awarded recognition to him on the 40th year of his CP/M creation. https://www.retrotechnology.com/dri/dri_16bit.html ----------------------- The beginnings of MS-DOS was an 8086 operating system that was written to support the equivalent CP/M-80 BDOS operating system calls under an 8086/88 processor. Also an equivalent 8086/88 BIOS was written closely following CP/M-80's BIOS scheme. The CP/M file system was NOT supported, instead what became the FAT-16 file system was developed. (I'm glossing over details, to make a point not a Wikipedia entry.) As for claims of outright source-code copying: inspection of source-codes by eye won't readily find copying. How do we know these things? the developer of what became MS-DOS, Tim Patterson, testified under oath to those facts, during litigation between an owner of the CP/M intellectual property (there were many at various times) and Microsoft. subsequently, Tim Patterson acknowledged his development process, on a Web site he created (which I've forgotten and I won't look up today). Patterson admitted using CP/M *documentation* to guide his development of what became MS-DOS. Repeating, documentation, not source codes. And in the general discourse about CP/M vs MS-DOS in the era, during times of litigation in particular, these facts were reported. and, simple inspection of early MS-DOS documentation shows anyone with knowledge of CP/M, that match between CP/M-80 BDOS calls and INT 21 calls of MS-DOS. as to the referenced article. The article referenced is from Aug 2016. "Software forensics lay MS-DOS, CP/M controversy to rest, By Brandon Lewis, Editor-in-Chief, Embedded Computing Design". It covers what is called a forensic review of alleged CP/M code using a toolset called CodeSuite. the review was done by the CodeSuite developer. The writer of the article makes the following claims among others:
The greatest possibility of copyright infringement came in the system calls, where, as seen in Figure 5, the numbering of the calls is almost identical across programs. For instance, in both MS-DOS and CP/M, 15 and 16 are the calls to open and close a file, respectively. Here we come to a gray area in that, while the system calls were implemented and used differently in each program, the similarities are undeniable. That being said, however, this is most likely a case of Microsoft not reinventing the wheel and sticking with the recognizable calls of the day. In copyright terms this is referred to as fair use. Did anyone buy MS-DOS as a result of the CP/M system calls? Probably not.
The article ends:
As for the CodeSuite findings, Zeidman presented them earlier this month at the Vintage Computer Festival that took place at the Computer History Museum in Mountain View, CA. He’s confident enough in his findings that he has offered a $100,000 reward for anyone that can disprove his findings that Microsoft did not copy source code from CP/M, and an additional $100,000 for anyone that can find Kildall’s mysterious secret function.
Until someone does, I think it’s time to put these rumors to bed. So, I observe the following in the article, in my own opinions.
1) It's a lot of tech-chat about some forensic methods of this CodeSuite software. Consequently, the article is really about CodeSuite, CP/M vs MS-DOS is an excuse. 2) The article author dismisses the claim about system calls as copyright infringement. That was the issue under litigation, among others, as I recall. In modern terms: can a set of API protocols be copyrighted? There were settlements, so the claim was not entirely bogus. 3) the article author misses the point about MS-DOS as a product of its time. Because of the close alignment between CP/M calls and MS-DOS calls, 8080-coded programs under CP/M-80 could be *mechanically translated* to 8086-coded programs under MS-DOS. As revealed in litigation, that was the intent of Tim Patterson, who literally had DRI manuals at-his-keyboard (he says) as he developed what became MS-DOS. So, go figure. 4) Factually, when IBM announced and distributed their IBM-PC with MS-DOS, producers of CP/M programs performed that very task of conversion. Why? To offer their old CP/M products to the new IBM-PC under MS-DOS. So the author's question: "Did anyone buy MS-DOS as a result of the CP/M system calls?" is not "absolutely not" but "certainly so, but they didn't realize why". Persons and companies bought the IBM PC to run software reasonably compatible with software on their previous CP/M-80 computers. My contemporary memory recalls, it took a few years for that transition of software products to complete (remember this was 1981). In those few years, developers moved from the CP/M platform to the MS-DOS platform (although CP/M systems remained in use for several more years). 4) Note the end of the article. The CodeSuite producer and distributor, goes to a conference - why? *to promote his product*. How best to promote it? Stir up a contemporary controversy, inject his product into it, and produce the same finding as was already known. To spice up his presentation, he adds a bogus prize that *no one will be able to claim*. Proving a negative is the hardest proof to achieve, it requires exhaustive checking of all possibilities. But the CodeSuite developer already knows, there's no source-code copying to be found. That was already settled in litigation; and also something an informed Intel processor programmer could tell you by eyeball in a matter of hours. Thus: a bogus claim and prize. Finis Regards Herb Johnson -- Herbert R. Johnson, New Jersey USA https://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net