Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/5/84; site omen.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!vax135!cornell!uw-beaver!tektronix!reed!omen!caf From: caf@omen.UUCP (Chuck Forsberg WA7KGX) Newsgroups: net.micro,net.arch Subject: Re: What if IBM Had chosen the 68000? Not what you think Re: 386 Family Products Message-ID: <258@omen.UUCP> Date: Wed, 20-Nov-85 07:03:23 EST Article-I.D.: omen.258 Posted: Wed Nov 20 07:03:23 1985 Date-Received: Thu, 21-Nov-85 05:58:56 EST References: <129@intelca.UUCP> <392@aum.UUCP> <225@l5.uucp> <533@scirtp.UUCP> <6139@utzoo.UUCP> <426@ecn-pc.UUCP> <427@ecn-pc.UUCP> <456@loo20 Nov 85 12:03:23 GMT Reply-To: caf@omen.UUCP (Chuck Forsberg WA7KGX) Organization: Omen Technology, Portland Lines: 63 Xref: watmath net.micro:12768 net.arch:2127 Summary: In article <456@looking.UUCP> brad@looking.UUCP (Brad Templeton) writes: >Ok, just what would have happened under these circumstances? I won't >say that this is gospel truth, but there is some evidence for it: > >1) The 68000 was only 16 bits at the time, no 68008 was to be had for > several years. This would have resulted in either special bus > multiplexing hardware (slow) or a 16 bit bus. This all adds up to > *cost*. The PC then would cost what the IBM-AT costs now. The > higher cost equipment means fewer people buy the machine, and very > few non-business customers buy it. How many hobbyists have ATs? > Result, little hacking in the mass market. Only the memory need be 16 bits wide, programmed i/o boards only need 8 bits. Besides, the Tandy 2000 and AT&T 6300 don't seem overpriced even tho they have a 16 bit bus. >2) CP/M Software (8080) is given no place to migrate. CP/M programs and > 6502 programs all have a high degree of processor loyalty that C programs > for 16 bit CPU's don't. You *can't* port a cp/m program to a 68000 > without a total rewrite. (This may be a good thing!) What this means > is that CP/M doesn't die, and maintains strength the same way the Apple > ][ and Commodore Architectures hang on. The result: CP/M and the 6502 > are the only serious contenders against IBM. With a 68000 based PC, you might have seen more PDP-11 programs ported. And, the p-system might have been more important (remember the p-system?) I'd gladly translate 8080 spurce code into C or 68k source code if I could have never had to use a segment register ... > [This is the most serious consequence. In order to advance the industry > to a new generation of architectures, you must *kill* the previous > generation. This only gets done if previous generation software can > be easily moved up. To do this, you need to have some level of > compatibility with the old stuff. In the case of the 8 bit generation, > only object level would do. In later generations, source level will > do. If you really want to advance the industry, you should go back > in time and push for a nice chip with a 6502 emulation mode.] I don't see where the PC killed CP/M for a few years. >3) 68000 programs are a lot larger than 8086 programs. A lot of programs > that might have shown up don't fit. On the plus side, this means a > bit of a push for larger memory, but only to achieve the same results. 68000 programs tend to be larger partly because there isn't an overriding need to limit their size. A 68k program that uses 16 bit ints and 16 bit offsets isn't that much larger than an 8086 small model program. And, a 32 bit 68k program tends to be smaller than a 8086 large model program. >4) Unix on micros is delivered a real blow. Chances are the IBM 68000 > has no memory managment. It's expensive and slows things down. > This means no Unix on this one. Sure there will be Unix for more > expensive 68000 boxes with no MMUs, but they will always be there. > Other multi-tasking systems that need an MMU like QNX are also hurt. OS9, Mini-Unix and Idris all operate on machines without memory management. -- Chuck Forsberg WA7KGX ...!tektronix!reed!omen!caf CIS:70715,131 Omen Technology Inc 17505-V NW Sauvie Island Road Portland OR 97231 Home of Professional-YAM, the most powerful COMM program for the IBM PC Voice: 503-621-3406 Modem: 503-621-3746 (Hit CR's for speed detect) omen Any ACU 1200 1-503-621-3746 se:--se: link ord: Giznoid in:--in: uucp