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February 26, 1987


By CBR Staff Writer

The upcoming version of MS-DOS being written specifically to take advantage of the capabilities of Intel’s 80286 microprocessor will be machine-specific, according to Microsoft officials quoted by Microbytes Daily. The California newswire reports that the still-unnamed operating system, alternately referred to by Microsoft as 286 DOS and New DOS, will be sold only to personal computer manufacturers, who will then be responsible for modifying the device drivers of the DOS so that it can be used only on their own machines. As Steve Ballmer, Microsoft vice-president of system software, explained it, a version of 286 DOS configured by Compaq to run on a Compaq 286, for example, will not run on other 286 machines, such as an IBM Personal AT or a Tandy 3000. He did point out that in some cases, 286 DOS may run on a different machine but might crash if an application program made a call to the hardware. Ballmer was quick to add that most applications will be compatible with New DOS and will run with any machine-specific configuration of the operating system. As expected, 286 DOS will have both real- and protected mode capabilities and support multi-tasking to allow for simultaneous execution of several applications. It will have at least 189 function calls against just 95 for MS-DOS 3.X. Some of the new functions include memory allocation, the ability to create threads, the ability to put characters on the screen in a certain position, and many of the functions that are handled by the BIOS Basic Input Output System under MS-DOS 3. The operating system will of course support MS-Net and MS-Windows. According to Adrian King, director of operating systems for Microsoft, real-mode 286 DOS will require about 80Kb of addressable memory, compared with the roughly 40Kb required by MS-DOS 3. Consequently, performance will be degraded by about 5% when current application software is run under 286 DOS in real mode. King said there will be no performance benefit from simply moving to 286 DOS. Microsoft officials are still reticent about giving an official release date for New DOS, although Ballmer did say that within six months, independent software vendors would be getting development kits. Ballmer speculated that new applications [created specifically for the 286 protected mode] will begin appearing about a year to 18 months from the time that the 286 DOS development kit is released. As for a native operating system for 80386-based machines, that is still a long way off, Microsoft told reporters and analysts at the meeting. Ballmer said a 386 DOS toolkit will be released sometime within the next two years. The characteristics of a 386 DOS were not explicitly defined. However, Microsoft indicated that the main differences between 286 DOS and 386 DOS would be in the way that 386 DOS takes advantage of the large linear address space and virtual machine capabilities of the 386 chip. Ballmer illustrated this with a demonstration of a prototype MS-DOS running on a Compaq Deskpro 386 where Lotus 1-2-3, dBase III, and other programs were each running independently on the screen at the same time. In each case, addressable memory had been segmented into 640Kb segments so that each application thought it was running on a separate machine. Microsoft chairman Bill Gates claimed, You can’t run 1-2-3 in background with any other product other than this one. Ballmer said the difference between the new class and existing class of applications is that the new class will take advantage of the large linear address space… Within two years, we should have the tools in place [for these applications to be created]. Depressingly, Jon Shirley, Microsoft president, commented on the long development time required to get operating systems to market by pointing out that MS-DOS 1.0 took only four months to prod-uce, MS-DOS 2.0 took one worker-year, and MS-DOS 3.0/3.1 took two worker-years, while the new 286 DOS has taken three-and-a-half worker-years. And, regrettably taking a leaf out of what should be one of IBM’s banned books, Microsoft has been throw

ing programmers at the problem. The number of programmers involved increased from 15 for MS-DOS 1.0 to 180 for 286 DOS. Shirley said the specifications for the new DOS are between 1,500 and 2000 pages long but declared hopefully that 386 DOS would not take another three-and-a-half years to develop because it would largely be based upon 286 DOS.

Software developers’ kit

Gates later confirmed this by saying that 386 DOS, and eventually 486 DOS, will not require a new generation of system software. Getting up to 32-bit, linear address space… will be a foundation to last for a long, long time. Bill Gates also talked about 286 DOS at Esther Dyson’s Personal Computer Forum, where he revealed that the software developers’ kit for the operating system would include the operating system itself, which will have 16Mb addressability, multi-tasking, memory protection, and exploit all the features of the 80286. Gates added, The operating system does not require the 80386. It meets the needs of developers who can work with 16Mb of 640Kb segments. Gates indicated that developers will have to wait several months more to get a Microsoft operating system that provides access to the large linear address space of the 80386. Yes indeed.

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