IBM PS/2 Model 50 Keyboard Controller

Posted on August 24, 2012 by Michal Necasek

Thanks to John Elliott, a ROM dump of the PS/2 Model 50 keyboard controller (an 8742 chip) is now available. The IBM PC/AT keyboard controller (KBC) ROM has been analyzed earlier.

So what exactly changed between the PC/AT and the first generation PS/2 systems? The obvious difference is the addition of auxiliary device (typically mouse) support. However, since the PS/2 architecture is noticeably different from the PC/AT, how many other changes are there in the keyboard controller? The answer is “fewer than one might think”. Continue reading →

Posted in IBM, PC architecture | 1 Comment

Book Review: Developing Applications Using DOS

Posted on August 17, 2012 by Michal Necasek

A Few Decades Late Book Reviews

Developing Applications Using DOS, by Ken W. Christopher, Jr., Barry A. Feigenbaum, and Shon O. Saliga
John Wiley & Sons, February 1990; 573 pages, ISBN 0-471-52231-7; $24.95

Developing Applications Using DOS is a surprisingly obscure book for what’s perhaps the best official-unofficial DOS programming reference. Unofficial because it was published by a 3rd-party publishing house (John Wiley & Sons), official because its authors worked as the lead DOS engineers at IBM (among other achievements, Barry A. Feigenbaum designed the ubiquitous SMB protocol in 1984).

Perhaps the relative obscurity of Developing Applications Using DOS has something to do with the fact that it concentrates on the ill-fated DOS 4.0; however, the vast majority of the book applies to both earlier and later versions of DOS. The book is—unsurprisingly, given its title—aimed at DOS developers, but some of the expository material may be useful to advanced DOS users as it explains certain performance characteristics and illuminates a few of the darker corners of DOS. Continue reading →

Posted in Books, DOS, IBM | 2 Comments

Why does Apple hate RSS?

Posted on August 12, 2012 by Michal Necasek

Last week I was setting up a new Mac and obviously the first thing I did was to upgrade the OS to Mountain Lion. No problems there. As one of the follow-up steps of the setup process, I tried to subscribe to this site’s RSS feed, something that worked extremely well with Snow Leopard’s Safari and Mail.

But oops—the RSS button didn’t show up. Yet it’s still there on a different Mac running Snow Leopard… Attempting to subscribe to one of Apple’s own many RSS feeds results in the following error message:

That’s very broken. One expects better from Apple. Continue reading →

Posted in Apple | Leave a comment

86-DOS Was an Original

Posted on August 10, 2012 by Michal Necasek

In case it wasn’t sufficiently obvious already: A forensic expert now confirmed that 86-DOS, née QDOS, and (by extension) MS-DOS were not copies of CP/M, either on source or binary level. This comes hardly as a surprise, despite years (nay, decades) of vague accusations against Tim Paterson and Microsoft.

Proving that 86-DOS was a copy of CP/M was always going to be very much an uphill battle based on what was known of the operating systems. 86-DOS ran on 16-bit 8086 systems, while CP/M at the time was 8-bit only (8080, Z-80); in fact the unavailability of CP/M on the 8086 was the sole reason why 86-DOS was written in the first place.

While 86-DOS was compatible with the CP/M API, it used a completely different disk management strategy (based on the FAT idea of Microsoft’s Marc McDonald) and DOS-formatted disks were never compatible with CP/M. In addition, 86-DOS supported the 8086 segmented architecture and accepted 16:16 far pointers for input/output buffers passed to DOS (because the segment address was passed in DS, small model programs, including those converted from CP/M, could ignore this feature). There was no equivalent in 8-bit CP/M. Continue reading →

Posted in DOS, Microsoft, PC history | 6 Comments

Another witness against WordStar

Posted on August 2, 2012 by Michal Necasek

Previous posts examined the question why IBM implemented the A20 hardware in the PC/AT, causing endless headaches to future PC hardware and software developers. WordStar emerged as a possible culprit, but no one would quite point the finger at it.

The OS/2 Museum is now in possession of the original MS-DOS Encyclopedia (1986) which identifies WordStar in print. This is the same book that Larry Osterman claimed to have been subject to a publisher recall; either Microsoft Press didn’t do a very good job of pulling the book from the shelves or Larry Osterman’s recollection is inaccurate, but the book isn’t very difficult to find. (However, at about 8 pounds, or nearly 4 kilograms, it is quite difficult to carry around!) Continue reading →

Posted in DOS, PC history, WordStar | 17 Comments

Book Review: Inside OS/2

Posted on July 23, 2012 by Michal Necasek

A Few Decades Late Book Reviews

Inside OS/2, by Gordon Letwin
Microsoft Press, February 1988; 302 pages, ISBN 1-55615-117-9; $19.95

Letwin’s Inside OS/2 was one of the first books devoted to OS/2. What sets Inside OS/2 apart from other OS/2 books published at the time is that it neither teaches how to use OS/2 or how to develop OS/2 applications, nor is it a reference book. Instead, Inside OS/2 explains why the system was designed the way it was designed; in fact, Gordon Letwin was one of the very few people who could have written such a book, having worked as chief architect of systems software at Microsoft. Continue reading →

Posted in Books, Microsoft, OS/2 | 17 Comments

Phantom 3.0

Posted on July 13, 2012 by Michal Necasek

As previously mentioned, the OS/2 Museum adapted the Phantom redirector example from the second edition of Undocumented DOS to demonstrate that the redirector interface was already fully implemented in the August, 1984 release of PC DOS 3.0, a fact apparently unknown to most authors of DOS literature.

The Phantom 3.0 redirector is now available for download in the form of a 360K floppy image. Kudos to the authors of Undocumented DOS for writing it in the first place. Needless to say, the code is provided as is, and although bug reports are welcome, no promises are being made as to if or when any issues might be fixed. Continue reading →

Posted in Development, DOS | 36 Comments

MacBook Pro with Retina display: What a letdown

Posted on July 8, 2012 by Michal Necasek

I’ve been a satisfied user of MacBook Pro laptops since mid-2006, soon after the first Intel-based Macs appeared. My current system is a mid-2008 2.6 GHz 17″ MacBook Pro which I’ve been overall quite happy with. However, the Core 2 CPU is getting rather old (especially its virtualization capabilities are nothing to write home about) and what’s worse, upgrading the system beyond 4GB RAM is very problematic.

I’ve been eagerly anticipating the June 2012 refresh of the MacBook Pro line. I was very excited when I first heard about the MBPs with Retina display, having had a few months of experience with a Retina-equipped iPad. But when I started the inevitable pre-purchase research, my excitement turned into wariness and then severe disappointment. Here’s why… Continue reading →

Posted in Apple | 3 Comments

On a dark, rainy night in April 1985…

Posted on July 7, 2012 by Michal Necasek

Update: Since the original document disappeared, a local copy is now provided.

When researching the history of computing, from time to time an unexpected gem turns up. The copy of Ray Ozzie’s notes from a 1985 meeting with Microsoft is one of such gems.

Between 2006 and 2010, Ray Ozzie was the chief software architect at Microsoft, a role he took over from Bill Gates. But in the early 1980s, Ozzie worked at Lotus on the Symphony product, and in 1984 left Lotus to start a company called Iris Associates. Iris worked on a software project which (several years later) became known as Lotus Notes.

At the beginning of April 1985, Ray Ozzie (Iris) met with Microsoft in Bellevue, Washington (Microsoft moved to Redmond in early 1986). From the notes it is obvious that Iris had an unusual level of access; besides providing answers from managers and engineers, Microsoft also disclosed the bulk of its org chart as well as internal project scheduling data, including unannounced projects. Continue reading →

Posted in DOS, Microsoft, Windows | 39 Comments

Minor site updates and summer time

Posted on June 19, 2012 by Michal Necasek

Summer is upon us, and as a consequence, site updates will be less frequent in the coming weeks.

Regular visitors may have noticed that after a long delay, the DOS history article on DOS 4 was finally published. Researching DOS 4 (apparently known as DOS 3.4 right up to the actual release) turned out to be surprisingly difficult… although “a lot of work” may be more accurate than “difficult”. DOS 4 was released at a time when the PC market was well established, with fully developed trade press. That meant there were lots of sources talking about DOS 4.

At the same time, DOS 4 was less than wildly popular and many authors more or less ignored it. That made finding accurate information about DOS 4 difficult, although there were certainly lots of dubious rumors floating around. Continue reading →

Posted in Site Management | 5 Comments