The Perfect Computer - 36 bits?
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From: Brian Inglis on 14 Apr 2007 10:20 On Fri, 13 Apr 2007 14:45:16 +0200 in alt.folklore.computers, Terje Mathisen <terje.mathisen(a)hda.hydro.com> wrote: >Brian Inglis wrote: >> On Wed, 04 Apr 2007 23:12:38 +0200 in alt.folklore.computers, Terje >> Mathisen <terje.mathisen(a)hda.hydro.com> wrote: >>> One 808x clone (possibly NEC?) implemented one of the BCD/ASCII opcodes >>> as documented, without noticing that the opcode had the decimal 10 as >>> the second opcode byte: On an Intel cpu you can/could replace that value >>> with something else, like using 16 to split a byte value into two hex >>> nibbles. >> >> Is that feature still supported under Pentium and documented anywhere? > >Yes, it is most certainly still there. > >> Anyone test to see what range of values work properly? > >It is effectively using a full DIV operation, with similar speed. :-( But on byte/nybble sized operands not supported by normal DIV. -- Thanks. Take care, Brian Inglis Calgary, Alberta, Canada Brian.Inglis(a)CSi.com (Brian[dot]Inglis{at}SystematicSW[dot]ab[dot]ca) fake address use address above to reply
From: Brian Inglis on 14 Apr 2007 10:28 On 14 Apr 2007 11:50:06 GMT in alt.folklore.computers, nmm1(a)cus.cam.ac.uk (Nick Maclaren) wrote: > >In article <5jp6f4-d3b.ln1(a)osl016lin.hda.hydro.com>, >Terje Mathisen <terje.mathisen(a)hda.hydro.com> writes: >|> Eric Smith wrote: >|> >|> >> I know quite a few people who used Z80s for that, and they >|> >> never really cut the mustard for mission-critical tasks >|> > >|> > I saw quite a few Z80s used for mission-critical critical tasks. >|> >|> Back in 1981 we had 12 (or 16?) channel 'Acoustic Emission' gear using a >|> dedicated Z80 per channel, this was used for monitoring stuff like >|> building platforms, offshore oil rigs and other relatively >|> 'mission-critical' applications. > >The context of this thread was computer communications, which has >rather different requirements. I can't tell you what the problems >were in detail, but they were more to do with "operating system" >functions and peripheral driving than simply not crashing due to >hardware problems. Our DataPac 3000 (X.25 telco network) interface boxes used Z80 chips and was as reliable as any other dataset equipment. Hated sliding and seating the full size flexible boards into the multiple edge connectors at the bottom end of the long, wide, narrow, welded case. -- Thanks. Take care, Brian Inglis Calgary, Alberta, Canada Brian.Inglis(a)CSi.com (Brian[dot]Inglis{at}SystematicSW[dot]ab[dot]ca) fake address use address above to reply
From: Morten Reistad on 14 Apr 2007 11:23 In article <qhhcrjkb57.fsf(a)ruckus.brouhaha.com>, Eric Smith <eric(a)brouhaha.com> wrote: >nmm1(a)cus.cam.ac.uk (Nick Maclaren) writes: >> No, but nor could the Z80 compete on industry-quality functionality and >> reliability. > >The Z80 was *much* more reliable than any PDP-11 system, which is not >surprising since it's an apples-to-oranges comparison. There were a lot of homebuilt systems where the designers were in the early learning stage for dynamic memory. Amazing that they were as stable as they were. >There's no reason why a Z80-based system could not have been made >as reliable as a PDP-11 system. Possibly some were, but certainly >not your average cheap hobbyist-grade Z80 computers, running cheap >hobbyist-grade software. I have seen Z80's in a lot of applications that has been running without a hitch for decades. It has been a mainstay in the alarm and monitoring industry. >> I know quite a few people who used Z80s for that, and they >> never really cut the mustard for mission-critical tasks > >I saw quite a few Z80s used for mission-critical critical tasks. > >More Z80s have been used for LIFE-critical tasks than the total >number of PDP-11 computers manufactured. The two most popular old traffic-light applications use Z80's with telex-grade serial communications between the lights to syncronise. -- mrr
From: Gene Wirchenko on 14 Apr 2007 20:31 jmfbahciv(a)aol.com wrote: [snip] >Of course. IIRC, IBM had a crisis in the 80s(?); the reason it >survived that one was due to having enough money to carry them >through. For a positive spin on this, see http://dumbentia.com/pdflib/ibmlose.pdf Sincerely, Gene Wirchenko Computerese Irregular Verb Conjugation: I have preferences. You have biases. He/She has prejudices.
From: Rich Alderson on 15 Apr 2007 15:06
jmfbahciv(a)aol.com writes: [talking at cross purposes] The *hard wired* numbers the original poster was talking about are things like tracks per cylinder, sectors per track, etc. etc., on disk drives for example. MONGEN does not put any of that into the monitor, ma'am. -- Rich Alderson | /"\ ASCII ribbon | news(a)alderson.users.panix.com | \ / campaign against | "You get what anybody gets. You get a lifetime." | x HTML mail and | --Death, of the Endless | / \ postings | |