Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site looking.UUCP Path: utzoo!watmath!looking!brad From: brad@looking.UUCP (Brad Templeton) Newsgroups: net.micro,net.arch Subject: What if IBM Had chosen the 68000? Not what you think Re: 386 Family Products Message-ID: <456@looking.UUCP> Date: Mon, 18-Nov-85 21:19:56 EST Article-I.D.: looking.456 Posted: Mon Nov 18 21:19:56 1985 Date-Received: Tue, 19-Nov-85 03:34:12 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> Reply-To: brad@looking.UUCP (Brad Templeton) Organization: Looking Glass Software Ltd. Waterloo, Ontario Lines: 64 Xref: watmath net.micro:12735 net.arch:2105 Summary: > > Think what the world would be like now if IBM had decided to go with > the Motorola family of chips for the PC series. WOW!! We would > really have some systems out there. IBM chose Intel for business, > not technical, reasons. I don't think Motorola would have sold IBM > twelve percent of their stock. Besides, IBM and Motorola compete > (or will be shortly) in a number of areas. 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. 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. [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.] 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. 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. If your goal is to make most people use a "nice" architecture (where "nice" is subjective but usually means "easy to get programs running under") then you must do three things: 1) Have a nice architecture! 2) Get people to stop using the old (not-nice) architectures 3) Get people to use the nice architecture #1 is engineering. #2 and #3 are marketing. To reach your goal, they CAN'T be ignored. You just can't wish them away. ============== As an aside, I won't argue that it's time for the 8086 to go. 64K Segments are getting me down. But I am sure it was the right chip to choose in 1980, when IBM-PC design decisions were made. Alsmost 5 years is a pretty good lifetime in this biz. -- Brad Templeton, Looking Glass Software Ltd. - Waterloo, Ontario 519/884-7473