Date: Wed, 20 May 1998 16:04:42 +0930 From: Greg Lehey <grog@lemis.com> To: jgrosch@superior.mooseriver.com, Wilko Bulte <wilko@yedi.iaf.nl>, freebsd-hackers@FreeBSD.ORG Subject: Re: Original PC (was: talk (fwd)) Message-ID: <19980520160442.U20476@freebie.lemis.com> In-Reply-To: <19980519232435.A3703@mooseriver.com>; from Josef Grosch on Tue, May 19, 1998 at 11:24:35PM -0700 References: <199805191808.UAA17299@dorifer.heim3.tu-clausthal.de> <199805192157.XAA04150@yedi.iaf.nl> <19980520144300.M20476@freebie.lemis.com> <19980519232435.A3703@mooseriver.com>
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On Tue, 19 May 1998 at 23:24:35 -0700, Josef Grosch wrote: > 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. No, that's not the case. 86-DOS was in fact the name under which Seattle Computer Products marketed their QDOS (Quick and Dirty Operating System). I bought a copy in about November 1980, along with a couple of S-100 boards. Does Thunderboard sound right? IIRC it was an 8 MHz 8086 and a combined 256 kB memory board [in my case, populated with only 64 kB] and UART, and it supported *up to 1 MB of RAM*. By comparison, the PC looked a little feeble when it was announced the following year. > 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. No, I don't believe that. The 8086 had been out for years, and I'm sure I saw 68Ks in 1980. Quite honestly, I think that IBM made the correct choice of hardware for that machine. Hardly anybody realised what a lasting influence it would have on the market, and getting the thing out the door was more important. Greg -- See complete headers for address and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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