gnu@l5.uucp (John Gilmore) (11/26/85)
In article <1000006@uicsrd>, cheong@uicsrd.CSRD.UIUC.EDU writes: > The IBM-AT has a 16 bit processor and support chips, 16 bit bus with 8 slots, > 1.2 meg floppy, nice keyboard and a disk controller card. The same computer > with a 68000 in it would cost just as much, or more than the 286 version. > How can you seriously suggest they would charge less? Choosing the 68000 versus the 80286, as in the IBM PC/AT, there is no cost issue. On the original IBM Feces, this would have been harder to justify -- remember, the Apple ][ and the Sol Terminal Computer were a big deal then. It would mean more chips (thus more space, more power), bigger connectors, etc. It does add up, and is not really needed for a "rock-shooter" like the cassette tape IBM PC. > >>2) CP/M Software (8080) is given no place to migrate... > >> You *can't* port a cp/m program to a 68000 > >> without a total rewrite. This is totally untrue. You can certainly write an 8080 or 6502 emulator that runs on a 68000; people have done so. It probably runs about the speed of an 8080. So it will run the old software during the transition period. You can also translate 8080 to 68000 assembler, and it's not all that hard. > >>3) 68000 programs are a lot larger than 8086 programs... > See other notes. Please show your benchmarks. I have yet to see a 68000 > Unix box that runs reasonably with much less than 1 meg of ram. I used > to own a Z-8000 Unix machine (ONYX) that was a very reasonable single user > system with 256K and a 3 user system with 512K. What does that have to do with the difference between 68Ks and 8088s? > Coherent ran at PDP-11 > levels on an IBM-PC with an 8088! Coherent is not Unix. OS/9 does this too, on 6809s. > Xenix on the 286 performs at a similar > level to 68000 systems costing more than twice as much, and can do it with > less memory. Unix on Fortune 68000 systems performs at a similar level to Intel 286 MDS sytems costing more than twice as much... Of course, if you compare the most expensive X system to the cheapest Y system there's a discrepancy. But what those machines actually do for the user often differs a lot. I haven't seen any 4.2 ports to the 286. I know 4.2 will run on a Turing machine, but perhaps on a 286 it won't perform well enough that anyone is willing to sell it? That problem doesn't exist on 68000s. > I'm not saying it would have been bad to see IBM choose the 68000. In fact, > they *did* market a 68000 machine at the same time as the PC. They mostly > aimed it as a "lab" machine. That's one reason it didn't sell well. > The others are (surprise, surprise) that it cost like an AT and couldn't > run any of the old software! It couldn't compete with the price of the 8088 > machine. This is wrong, or highly misleading. IBM bought a company that was making 68000-based lab instruments and renamed it IBM Instruments. This 68000 based machine came standard with a-to-d and d-to-a but the keyboard was an option; it was intended to be controlled from knobs and switches. It was not a personal computer and was not intended to be; it was supposed to fit in a rack and quietly do fft's or something. --- Well, if you made it down this far I guess you deserve an answer. Sources closer than me to the decision have claimed to me that IBM wanted to build a Z80 system (a "morrow clone?") but they were talked out of it by Microsoft, who knew the faster and more capable 16-bit chips would blow the CP/M systems away. (IBM isn't very technically sophisticated in micros even today, e.g. they don't really know what they are getting until after they get it. Witness the 80286 that doesn't run 8086 code under the 286 opsys. Well, it's fixed for the 386 -- they hope.) IBM went to Intel and went to Motorola and may have even paid a courtesy call on National, but Intel was the only place that would commit to delivering 250,000 chips for the first year's production of IBM Feces. At that point Motorola was still ramping up and could supply folks like Sun or Fortune, but not e.g. Apple or IBM. So Intel's "design? No, just build the thing" approach actually *did* win them the low end 16-bit market, because they could produce a quarter of a million chips a year once a big customer existed. A shame, but consider this: If IBM *had* picked the 68000, who could all us 68k fans feel superior to?
kds@intelca.UUCP (Ken Shoemaker) (12/07/85)
> Choosing the 68000 versus the 80286, as in the IBM PC/AT, there is no > cost issue. On the original IBM Feces, this would have been harder to Not so if you want to add memory management and protection... > You can also translate 8080 to 68000 assembler, and it's not all that > hard. The hard part is emulating the flags on arithmetic operations. This is really about the only thing in the 8086 that is compatible with the 8085. > > > >>3) 68000 programs are a lot larger than 8086 programs... > > See other notes. Please show your benchmarks. I have yet to see a 68000 > > Unix box that runs reasonably with much less than 1 meg of ram. I used > > to own a Z-8000 Unix machine (ONYX) that was a very reasonable single user > > system with 256K and a 3 user system with 512K. > > What does that have to do with the difference between 68Ks and 8088s? > > > Coherent ran at PDP-11 > > levels on an IBM-PC with an 8088! > Coherent is not Unix. OS/9 does this too, on 6809s. But then again, so does xenix and venix run on an 8088... > > > Xenix on the 286 performs at a similar > > level to 68000 systems costing more than twice as much, and can do it with > > less memory. > > Unix on Fortune 68000 systems performs at a similar level to Intel 286 MDS Last I looked, I could get an AT clone for <$5000, and run xenix on it... How someone can claim that a 68k with an external MMU is cheaper than a 286 with in internal MMU...don't forget board cost! BTW, is Fortune still in business? > consider this: If IBM *had* picked the 68000, who could all us 68k > fans feel superior to? Probably Motorola feces (:-)) -- yes, some uncomplicated peoples still believe this myth... Ken Shoemaker, Santa Clara, Ca. {pur-ee,hplabs,amd,scgvaxd,dual,qantel}!intelca!kds ---the above views are personal.