Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site ecn-pc.UUCP Path: utzoo!watmath!clyde!cbosgd!ihnp4!inuxc!pur-ee!ecn-pc!wdm From: wdm@ecn-pc.UUCP (Tex) Newsgroups: net.micro,net.arch Subject: Re: What if IBM Had chosen the 68000? Not what you think Re: 386 Family Products Message-ID: <428@ecn-pc.UUCP> Date: Tue, 19-Nov-85 10:07:16 EST Article-I.D.: ecn-pc.428 Posted: Tue Nov 19 10:07:16 1985 Date-Received: Wed, 20-Nov-85 20:26:37 EST References: <129@intelca.UUCP> <392@aum.UUCP> <225@l5.uucp> Reply-To: wdm@ecn-pc.UUCP (Tex) Organization: Cybotech Product Development Lab Lines: 120 Xref: watmath net.micro:12753 net.arch:2115 In article <456@looking.UUCP> brad@looking.UUCP (Brad Templeton) writes: >> >> 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. > >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. Get serious!! Does the macintosh cost as much as the AT? The Amiga? The ST? No of course not. Face it, the bus interface hardware accounts for a tiny fraction of the overall cost. Given the cost/performance ratio, adding a sixteen bit bus would make a lot of sense. > >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. Is a sizable percentage of ms-dos software old cp/m software? It would surprise me if it were. Or maybe I should say it would sur- prise me if it weren't rewritten in a major way, seeing as how the operating systems are not at all alike. I would have rather they were rewritten for the 68000 environment. > > [This is the most serious consequence. In order to advance the industry > to a new generation of architectures, you must *kill* the previous > generation. I guess that explains why there are no ibm 370- type systems around anymore. What? You say there are? Well I guess that means we haven't advanced since the mid-60's. There is absolutely no need to "kill" off the previous generation of architectures. In fact, this comment contradicts your point 2. > 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.] Are you schizo or what? Make up your mind! I never said emulation was desirable. > >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. If you mean there are alot of large 68k application programs out there, then I agree. If you mean that a program for a given task is larger on the 68k than on the 808/8/6 then I disagree totally. Look at any of a number of benchmarks that have been written. > >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. The IBM PC has no memory management. What is your point here? It makes no sense. You are incorrect in saying that because this imaginary machine has no mmu, there would be no unix (as you point out in the next sentence) since there are versions of unix right now that do not need memory management. Anyway, who said our ibm 6800 has to run unix? Why not os-9, or any or a bunch of operating systems? > >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! Ok, I suggest the 68000 here. > 2) Get people to stop using the old (not-nice) architectures Not all that many people were using the 808X before IBM anyway. > 3) Get people to use the nice architecture Anything that IBM sells is going to be used, if they support it like they did the PC. > >#1 is engineering. #2 and #3 are marketing. To reach your goal, they >CAN'T be ignored. You just can't wish them away. Who is wishing them away? My scenario is what if IBM chose the 68000 instead of the 8088 for their PC. Am I to believe that they wouldn't have marketed it as ardently as they did the 8088-based PC? >============== > >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. Then how about presenting some real arguments to support your argument? Arguments like, the ibm 68000 probably would not have had Unix support, or false arguments like the 68000 uses more memory to achieve the same task, do little to support what you are trying to say. >-- >Brad Templeton, Looking Glass Software Ltd. - Waterloo, Ontario 519/884-7473