The Perfect Computer - 36 bits?
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From: Joe Pfeiffer on 30 Mar 2007 00:29 Andrew Reilly <andrew-newspost(a)areilly.bpc-users.org> writes: > On Thu, 29 Mar 2007 13:23:46 +0000, Nick Maclaren wrote: > > > Dunno. I wasn't talking at that level anyway. If DEC had taken > > the decision to produce a new micro-PDP-11, there would have been > > a LOT of such issues to resolve. > > I played with a nice LSI-11 box at Uni. It wasn't new then, but there > were plenty of 68000 and a few Z8000 systems around by that time too (both > of which could reasonably be called -11 clones). I'd agree with children...
From: Tarkin on 30 Mar 2007 01:10 On Mar 30, 3:46 am, CBFalconer <cbfalco...(a)yahoo.com> wrote: > Nick Maclaren wrote: > > ... snip ... > > > No, but nor could the Z80 compete on industry-quality functionality > > and reliability. I know quite a few people who used Z80s for that, > > and they never really cut the mustard for mission-critical tasks > > (despite being a factor of 10 or more cheaper). > > Nonsense. I had 8080 based communications systems that ran > continuously (no restart) for 2 to 3 years, until brought down by a > mains power failure. > > -- > Chuck F (cbfalconer at maineline dot net) > Available for consulting/temporary embedded and systems. > <http://cbfalconer.home.att.net> > > -- > Posted via a free Usenet account fromhttp://www.teranews.com 8080 != Z80. ISTR reading from a few different places that early Z80's were 'twitchy'; that's also why there are 'undocumented' opcodes- those opcodes did not work reliably until the kinks were worked out of the (wafer production [?]) process. TTFN, Tarkin
From: Jan Vorbrüggen on 30 Mar 2007 02:53 > Did the Alpha have a BCD add instruction? If not the shifting and > masking to add 4 bits at a time would be very slow. No, it doesn't. And you don't do BCD arithmetic on a binary machine that way - Terje recently explained how it's done. With 64-bit integers, you can do up to 16 digits in one go. My comment, further up in the thread, about translating or recompiling addressed this issue: AFAIK, the Cobol compiler on the Alpha used 64-bit integers natively where the VAX compiler was forced to use BCD (which was slow on later models anyway, I believe). Jan
From: Jan Vorbrüggen on 30 Mar 2007 02:58 > Hmmm. If the VAX and ALPHA instruction sets are now public source then > clones can be made. They already exist, but in software rather than in hardware. And if you want to use VMS natively, buy an Alpha or an Itanium system. > To keep the general public happy running programs by clicking a mouse > will be needed. Someone is going to have fun converting clerical > software like OpenOffice. VMS has all that, no need to re-invent the wheel. > VAX/VMS the reliable alternative to Windows PCs. For sure! Jan
From: Jan Vorbrüggen on 30 Mar 2007 03:01
>>The distinguishing feature of VMS, IMNSHO, is the VMScluster, with the >>connection manager and the lock manager as the main supporting pieces of >>software of that capability. TOPS-10 or -20 never had anything like it. >>Where was Leslie Lamport before this happened? (A lot of the VMScluster stuff >>is based on his ideas.) > Oh? That would come as a surprise to the students at LOTS after 1984, when we > clustered the three 2065s, and eventually the Systems Concepts SC-30M, on the > CI bus that came with the HSC-50s and RA-81 disks (all invented, BTW, for the > 36-bit Jupiter). Cross-system resource sharing, central login (a Stanford > innovation that was taken back by DEC^WDigital for Tops-20 v6.1), and so on. Was that as closely coupled at all levels of the OS as is the VMScluster? In any case, who wrote the software you mention above? Jan |