Date: Tue, 19 May 1998 23:24:35 -0700 From: Josef Grosch <jgrosch@superior.mooseriver.com> To: Greg Lehey <grog@lemis.com>, Wilko Bulte <wilko@yedi.iaf.nl>, freebsd-hackers@FreeBSD.ORG Subject: Re: Original PC (was: talk (fwd)) Message-ID: <19980519232435.A3703@mooseriver.com> In-Reply-To: <19980520144300.M20476@freebie.lemis.com>; from Greg Lehey on Wed, May 20, 1998 at 02:43:00PM %2B0930 References: <199805191808.UAA17299@dorifer.heim3.tu-clausthal.de> <199805192157.XAA04150@yedi.iaf.nl> <19980520144300.M20476@freebie.lemis.com>
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On Wed, May 20, 1998 at 02:43:00PM +0930, Greg Lehey wrote: > On Tue, 19 May 1998 at 23:57:14 +0200, Wilko Bulte wrote: > > As Oliver Fromme wrote... > >> In list.freebsd-hackers Mike wrote: > >>> [...] > >>> I've always heard (I have no motorola experience, yet) that motorola asm > >>> blows x86 away when it comes to efficiency. A friend I have develops for > >>> Be and he's always ranting about it. :) > >> > >> He's right. The x86 has 4 general-purpose registers, each of > >> them 16 bits (they were extended to 32 bits in the 80386) and > >> 4 address registers of the same size. And there are certain > >> restrictions on their usage, e.g. you can only use the CX > >> register as counter in the "loop" instruction etc. > >> > >> On the other hand, the Motorola 68k has 8 general-purpose > >> registers of 32 bits and 8 address registers (also 32 bits). > >> There is no restriction on their use, except that the 8th > >> address regsiter is the default stack pointer. > >> > >> I programmed on both architectures in assembler, and I have to > >> say that the 68k is definitely easier to program, and the > >> higher number of registers allows for efficient programming. > >> > >> Maybe it was the biggest mistake ever made in computer history > >> when IBM selected the 8088 for their first PC back in 1979. > >> (Or was it 1978? Don't know, I probably couldn't even spell > >> the word "Computer" correctly back then.) If they used the > >> 68000 -- which was already available at that time -- we would > >> have less problems today, I guess. > > > > An attractive (to me ;-) explanation is that IBM did not want to use the > > 68K because it was a threat (performance wise) to their high profit machine > > range. > > > > Urban legend or not, it sure sounds OK ;-) > > I just realized what this thread was about after deleting a lot of > messages unread, so if I repeat something that has already gone past, > please forgive me. > > Did it really take IBM so long to develop the PC? My recollection was > that it was a sort of half-hearted effort after the devastating > success of the 5100. In any case, the obvious reason for the choice > of processor was the software available--CP/M 86 and 86-DOS for the > 8088, nothing for the 68K. On top of that, the 8088 was cheaper > because it had 8 bit memory (remember that most chips in those days > were single bit). I don't think they had the slightest concern about > attacking their mainframe machines, which were as fast as they needed > to be (quite literally). > If memory servers me right, the original IBM-PC was a semi rouge operation based in Boca Raton, Fl. I remember reading in Byte at the time, back in the days when Byte was worth reading before it became just another media toady for Microshit and this is covered in "Revenge of the Nerds" or "Accidental Empires", the suits at IBM were very nervous about missing the boat with the PC. This is 1979-1980. The Apple II was selling like cold beer at a double header in the middle of august all thanks to VisCala and Steve Jobs. The comment was "If we do this like a normal (IBM) product it'll take 4 years to ship." I think CP/M 86 and 86-DOS was after the introduction of the IBM-PC. I think the reason they went with Intel instead of Motorola was Intel told them the chip was ready, and Motorola told them 6 months. Intel lied and shipped late. Motorola shipped when they said they would but by that time they had missed their window. Of course this was 20 years ago and I could just be hallucinating again ;-) Josef -- Josef Grosch | Another day closer to a | FreeBSD 2.2.7 jgrosch@MooseRiver.com | Micro$oft free world | UNIX for the masses To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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