Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!rutgers!clyde!cbatt!ihnp4!houxm!hjuxa!catnip!ben From: ben@catnip.UUCP (Bennett Broder) Newsgroups: net.micro.pc Subject: Re: MS/PC DOS? Message-ID: <404@catnip.UUCP> Date: Tue, 28-Oct-86 22:38:46 EST Article-I.D.: catnip.404 Posted: Tue Oct 28 22:38:46 1986 Date-Received: Wed, 29-Oct-86 21:50:45 EST References: <985@husc2.UUCP> <394@catnip.UUCP> <4058@amdahl.UUCP> Reply-To: ben@catnip.UUCP (Bennett Broder) Organization: The Broder Residence, Holmdel, N.J. 07733 Lines: 80 Keywords: MS-DOS, PC-DOS In article <4058@amdahl.UUCP> kim@amdahl.UUCP (Kim DeVaughn) writes: >> >I am an experienced user of PC-DOS, but I am still unclear on >> >the exact differences between MS-DOS and PC-DOS. >> >In article <394@catnip.UUCP>, I write: >> There is little if any difference between MS-DOS and PC-DOS. They are >> both the same OS, but PC-DOS is supported by IBM instead of Microsoft >> or another hardware vendor. >> >> In article <985@husc2.UUCP> shields@husc2.UUCP (shields) writes: >Sorry, but I couldn't disagree more! > >MS-DOS is a generic product which is sold to OEM's. It provides all of >the system functions and calls that are accessed via interrupts above 20h >(i.e., int 20h, int21h, etc.) This generic, base system is sometimes >slightly customized by the OEM (IBM does this to a minor degree, I'm told). >The basic operation of MS-DOS, and the functions provided via these rupts >are very well defined and consistent from vendor to vendor. But that's >where it stops. Exactly. >All of the functions/services that are provided by the BIOS are up to >the individual vendor to implement, and are implementation specific. On >PClones these are things like rupts 10h - 1Fh, which provide services >for Video I/O, RS232, keyboard, printer, Basic, floppys, etc. (at the >BIOS level). Then there are what are usually called H/W rupts (08h - 0Fh) >on PClones; these too, are implementation specific. >There are several machines that run MS-DOS, but are in no way compatible >with IBM PC's or PClones, and have vastly different H/W and BIOS functions. >For example, my Fujitsu Micro-16s runs MS-DOS (2.11, currently), but >very little PC software (unless the s/w has been written to be MS-DOS >compatible, or a port has been done specifically for the Fuji machine). Yes. And this issue is refered to as "PC compatiblity". There are machines that are very PC compatible that run MS-DOS, and machines that are not, but the MS or PCDOS code and functionality are the same. >The term PC-DOS is usually used to refer to the collection of MS-DOS >*and* the BIOS and H/W rupt support as implemented by IBM PC's (and "true >compatibles"). The BIOS part may be realized in s/w on a floppy, or may >be in ROM, or a combination of the two. Where did you see that definition? When I purchased PC-DOS, it came in a box with a manual and diskettes. There were no BIOS ROMS in there. And, as I type this, my keystrokes are being processed by those very same BIOS ROMs, although my machine is running multiuser Xenix, not PC-DOS. Quite simply, the BIOS routines are provided by the vendor to give developers a consistant and well defined means to access the actual hardware. Although they are used by DOS, Xenix, CP/M 86, PICK and other operating systems, BIOS routines are *not* a part of the O/S. In fact, many of the compatibility problems that plague owners of non-IBM hardware occurs because developers access hardware directly, bypassing the BIOS routines. But even in the case of the totally incompatible BIOS supplied with your Fujuitsu and several other 8086 based machines, the interface between a program and MSDOS is consistant from vendor to vendor, while at the same time, the operating system can do nothing to help or hinder calls that an application program makes directly to the BIOS. >I short, while the MS-DOS part of the system s/w may be portable from >one vendor's machine to another, the BIOS/etc. parts may or may not be, >and then only if the machines are PClones. I think you are mistaking the issue of whether MSDOS=PCDOS with that of PC compatibility. I can take a copy of MSDOS from my employers AT&T 6300 and run the same programs I run with PC-DOS. I could take my copy of PC-DOS to your machine, and you would *still* not be able to run most PC software. In short, compatibility is determined by the hardware and the BIOS, not by whose version of DOS you buy. -- Ben Broder {ihnp4,decvax} !hjuxa!catnip!ben {houxm,topaz}/