test-drb November 2005

test-drb@ccmp.vtda.org

255 participants
692 discussions

by ajp166＠bellatlantic.net

> >Subject: RE: Smithsonian gets it wrong > From: "Vassilis Prevelakis" <vp at cs.drexel.edu> > Date: Sat, 12 Nov 2005 18:54:52 -0500 > To: cctalk at classiccmp.org > >"a.carlini at ntlworld.com" <arcarlini at iee.org> wrote: >> > Vassilis Prevelakis wrote: >> > Hello?? The label says its a *MICRO*VAX, and if its a uVAX, then >> > its not a mini. Also, calling the baby-sized uVAX a mini gives >> > visitors who may have never seen a mini-computer the wrong idea as to >> > what a mini-computer looks like. Sure I'll accept that its *compatible* > >> I'd not call the MicroVAX a mini, but it *is* a VAX. > >Actually I agree, I got carried away in my original posting. > >My main objection is the mini designation. The uVAX is not a mini. > >In the early 80s IBM produced a set of ISA cards for their original >PC. These cards implemented a large subset of the IBM 370 architecture >and the PC could boot some 370-compatible OS (I do not recall which >one). The called it the IBM PC/370. It was a 370 but I wouldn't >call it a mainframe, nor would I place a card next to it saying >IBM 370 MAINFRAME [...], and this is the model PC/370 >produced in (say) 1984. > >**vp Your still skating on thin ice. The whole concept of a mini was that a mini was not a maxi. there was never a clear delineation and those that got the term like the PDP-8 were minis because they were distinctly smaller that most peoples perception of computer at that time (multiple 6ft high racks.). By 1985 that idea meant a MicroVAX was a mini and the VAX was the big fella. But by then we called the little ones micros and the big guys something else other than minicomputers. Sorta like for the last 15 or so years PC universally applies to personal computer and it's implied that it is wintel. But from about 1970ish to around 1981 PC meant Personally owned Computer and it could be anything! For example I was offered a Cincinatti Millichron CM2000 in 1973 for $2000 (price of a new truck) and if I'd done that it would have been my first PC even though the box was 19Wx11Hx28D and it weighed at least 80 pounds without the ASR33. So terms like mainframe, mini are sometimes hard to pin down.During the '70s the mid 60's idea of mini became smaller and machines like the VAX and Eclipse were called superminis. But that left the desktop Novas and PDP-8/e/f/m to be called what? Micro was easier as it really had to contain the core processor on one or very few chips that were LSI or VLSI. So without wrapping the timeframe context around the words there is considerable drift in what the images it conveys. For context when minicomputer was first coined and applied a womans skirt was calf length and a miniskirt was, well, too short safely to bend over without risk. But even that industry had the micromini. ;) Allison

18 years, 8 months

FPGA VAX update, now DIY TTL computers

by ajp166＠bellatlantic.net

> >Subject: Re: FPGA VAX update, now DIY TTL computers > From: woodelf <bfranchuk at jetnet.ab.ca> > Date: Sat, 12 Nov 2005 10:49:26 -0700 > To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> > >Allison wrote: > >>Must only be using 7400 and 7404s doing it the hard way. As far back >>as '68 ALU blocks were availble, sure they cost $4 each then but the >>chip savings was there. >> >> >I was thinking 7401's ( 2 input OC Nands) and 7414's ( hex schmitt >trigger). > >>Likely you'll never build it. >> >True, but the chalenge is there. PS if I add as many displays as you say >I need this >will at least look impresive. > >> Moving up just one step integreation wise >>is the 7483 (it equivilent is PDP8 era) full adder. That alone will cut >>the ALU chip count. >> >> >> >This is 18 bits ... 2 or 3 or 6 or 9 is needed here, not 2 or 4 or 8 >or blah! 16 :) So throw away the excess bits. It's still cheaper. Also there is a Single full adder TTL part the 7480. >>My fun was not replicating the archetecture in an acient way but using the >>most MSI TTL parts I could get to replicate it in a moden way. IE: can I >>build a TTL PDP-8 with 1kx4 MOS ram in minimum TTL count for everything >>else. One can simplify that to working replica rather than exact replica. >> >> >> >The 8 reduces well for modern chips but the lack of a TTY or a high >speed punch/reader and a >dumb terminal is what is preventing me from build a 8 in 3 CPLD's. Well the punch is ahrd but a HS reader is trivial to build AS it's been done many times. as to putting it CPLD or FPGA, yes you could but I'm saying/staying in TTL with available SSI and MSI functions it's possible to be chip count reasonable. >>The difference is 2 'ls273 for a 16 bit register or 8 LS74s. But it goes >>further with fewer sockets, pins and wires, power and debug time. That >>also relects reliability once working as used parts are going to be >>a bit shakey untill (re)infant mortaility is again worked out from >>removal stresses. That may be minor but with a 200-400 peice TTL system >>you would be surprized unpleasently with how bad bring up can be if there >>is any uncertanty in the parts used. >> >> >> >I plan to get new parts, but this TTL design will be slower version the >CPLD cpu I am building, >I am going backwards here since other the IDE drive and moden ( 90's ) >memory don't want >to have rely on M$ if I want to make a hardware change. ( Ok not quite >true as I'll be using >windows for PCB and CAD work ). I have nearly 30 IDE drives all under 500mb I can build around. Its easy to make them look like a RK05 or whatever to a PDP-8 databreak interface. What MS does next year or even lsat years does not impact me at all. >>When I did the 200 peice TTL system it was 1972 into 73 and we were using >>the then common silicone plastic TTL aka the gray plastic and those were >>not reliable. That system took over a month to debug between wiring >>errors, timing errors (races and spikes) and new but partially dead chips. >>and after it was working for about three months after it was cranky when >>hot till we weeded out a few more bad actors. >> >> >> >This is making me think twice to goto LS. Now what I need help is with >the J/K flip flops (TTL). 7473 -- "Do not change J/K while the clock is high." But I want to >STOBE J/K when the clock is high for a D F/F. Will this work in practice? The clock change for 7474 is postive side and 7473 is negative going side. That only a start, their logically differnt animals. Also some types of D ff can have a metastable state (both outputs high or low) under some cases! >>One thing I'd suggest for those building something greater 50 TTL is lots >>of LEDs to indicate the state or status of a block of logic plus the ability >>to slow the clock if possible to near DC so you can watch it do stuff >>without a fast logic analyser. It's a great fault finding tool. >> > >PS. I got a $5 brick for this years project. :) > >>Theses days free PC power supplies (usually free scrap AT form factor) >>and cheap brick form factor switchers make 20A at 5 volts a trivial deal. >> >> >No wait the brick err door stop is the old PC. Ah foo. Allison

18 years, 8 months

Smithsonian gets it wrong

by vp＠cs.drexel.edu

"a.carlini at ntlworld.com" <arcarlini at iee.org> wrote: > > Vassilis Prevelakis wrote: > > Hello?? The label says its a *MICRO*VAX, and if its a uVAX, then > > its not a mini. Also, calling the baby-sized uVAX a mini gives > > visitors who may have never seen a mini-computer the wrong idea as to > > what a mini-computer looks like. Sure I'll accept that its *compatible* > I'd not call the MicroVAX a mini, but it *is* a VAX. Actually I agree, I got carried away in my original posting. My main objection is the mini designation. The uVAX is not a mini. In the early 80s IBM produced a set of ISA cards for their original PC. These cards implemented a large subset of the IBM 370 architecture and the PC could boot some 370-compatible OS (I do not recall which one). The called it the IBM PC/370. It was a 370 but I wouldn't call it a mainframe, nor would I place a card next to it saying IBM 370 MAINFRAME [...], and this is the model PC/370 produced in (say) 1984. **vp

18 years, 8 months

Sorry to post this to the list (5155 PSU diagrams)

by ard＠p850ug1.demon.co.uk

Sorry to bother the whole list with this... Can the chap who wants the schematics for the IBM 5155 PSU (Portable PC) please contact me (or Dave Colver directly (secretary at hpcc.org)). He tells me they're scanned (and about 1.7Meg). -tony

18 years, 8 months

INCAA - PIT

by jlewczyk＠his.com

>Date: Fri, 11 Nov 2005 16:23:17 +0100 >From: Thomas Seidel <thomas.seidel at gmail.com> >Subject: INCAA - PIT >To: cctech at classiccmp.org >Hi, > >a colleague just picked up the board of an "INCAA PIT" and handed it over to >me. Looks like a programmable interface converter, it has two DB25 >connectors and a 6800 CPU. The two ROMs are labelled "PIT 1985" and there is >a bit of RAM (SRM2064 & TMM2016) . What is the box doing? Are there any >manuals available? It's possible to program the CPU via the DB25 connector? >Any hints? > >TIA, >--Thomas I googled "INCAA PIT" and found this link which is a list of documents avaible which includes "INCAA, PIT Users Manual, 1984, KP10" http://web.ukonline.co.uk/apricale/nonfic.html

18 years, 8 months

Collectables?

by cclist＠sydex.com

I just found an unused bare S-100 backplane PCB marked "EXP-4 Rev. 2" and "(C) 1975, IMS Assoc. Inc.". I'm assuming that it's for the IMSAI 8080, but am not certain. I've also discovered a bare Polymorphic Systems backplane from about the same time. I'll throw in the 4 edge connectors that were taped to it. It has pads for rectifiers, caps and what looks like a regulator on it. Let me know if you're interested. Cheers, Chuck

18 years, 8 months

More on my HP7245A problem

by ard＠p850ug1.demon.co.uk

I've been doing some more fiddling with that HP7245A printer/plotter. On the ROM/RAM board there are 8 9216s, arranged to give an 8K*16 program storage space. And also 4 off 82S123 PROMs arranged to give 64words*16, probably for some kind of parameter storage. Those last 4 chips are socketed. Test 02 does appear to be the ROM test (as on the -B model). On my machine it seems to access all the program ROMs and the first pair of 82S123s. It then gives up with error 54(8). I have rpelaced the sockets (with nice turned-piu ones), no change. By swapping the ROMs around, I think I've discovered that the test is a simple cheacksum, independant of the address.In particular, if I swap round the 2 sets of PROMs (in the test mode), it fails with error 56(8). And if I put them back in the right sockets, and then swap round the 2 ROMs in the low bank, it fails with code 53(8) This leads me to guess that the error codes (in octal) are : 53 : U15 (PROM A MSB) 54 : U10 (PROM A LSB) 55 : U16 (PROM B MSB) 56 : U11 (PROM B LSB). And that U10 is genuinely the problem in my machine (i.e. not the socket, PCB traces, or address decoder, all of which I have checked anyway). Curiously, all 4 PROMs have the same HP part number, but I suspect that's the code for a blank chip, and that the contents of each chip is different. OK, it's a long shot, but does anyone have a dead 7245A that they can pull these ROMs from? Or any idea as to what the contents should be? -tony

18 years, 8 months

Variable Word length CPU

by stevew＠ka6s.com

"Dwight K. Elvey" <dwight at ca2h0430.amd.com> Wrote: >Hi >My thought is to make a variable word length processor using >a single bit ALU. Of course, I've been thinking in terms of a relay >based machine. >Dwight Hi Dwight, Having helped design a variable word length computer (B1000 series machines (B1955, B1965), I'm of the opinion that it isn't a useful construct. Burroughs justified the idea by saying they ran "microcode" on the hardware. It was really a basic machine language just like any other computer. The only real difference was that all the compilers compiled down to intermediate languages which were run on interpreters. It didn't yield very good performance even though the hardware wasn't that slow for it's era. There are a couple of interesting side effects of the choices they made. They needed to have a variable word length rotate capability, and also chose to address memory on bit boundaries. If you had a 13 bit word length, then memory delivered 13 bit elements to you (wasting alot of bandwidth in the process since it was organized by 32...) You also need the ability to pull off the carry bit from any particular point in the ALU. If I were the Burroughs architect, I wouldn't have gone to those extremes knowing what I know now. Steve Wilson

18 years, 8 months

Visual Technology - off brand

by beclassic＠att.net

This Company's products are also scarce on the web - maybe they were just "another clone" (although luggable). A year or so ago I located a prior employee who gave some background, including that he might still have the schematics. They were made 1984-86. I've had no interest in the Visual 1083 I want to place, but I'm hoping a touch of off-brand discussion might change that. -------------------- my earlier post: I want to find a home for my 5150 and a few other items. Prefer a collector rather than ebay, but I would still hope to get a nominal consideration in return. I'm in South Carolina. [] IBM PC (5150) set up as a clone XT. It has a 10mb hard drive and dual half-height floppies. Three original manuals with disks: DOS (3.00 or 3.30?), Guide to Operations (2.05) and Basic. Keyboard is original. Not sure what kind of video interface, but the CGA monitor works fine on it. [] IBM CGA monitor (5153). [] Visual 1083 - Commuter. This description mentions an LCD display, but that is not a part of mine. No disks, but it boots with the DOS from the IBM. http://www.thepcmuseum.net/details.php?RECORD_KEY%28museum%29=id&id(museum)… [] nice AT-style desktop box and 15" SVGA monitor (will either be Sony or Mag). I raided the box for the QDI motherboard, but I have another (name?) and a Pentium 200 that previously worked in this box. Not sure whether I'll keep the 6 meg hard drive. Couple of keyboards. [] box of miscellaneous I/O boards + modem . . . mostly from Boca for 16-bit ISA. [] maybe some software for PC - Clipper, Wordperfect?? - I'll be checking. I can take pics and send emails if needed and will try to firm up answers to some questions I raised for myself. I can answer on this board if someone wants an answer that way. bill

18 years, 8 months

Smithsonian gets it wrong

by ajp166＠bellatlantic.net

> >Subject: Smithsonian gets it wrong > From: "Vassilis Prevelakis" <vp at cs.drexel.edu> > Date: Sat, 12 Nov 2005 13:29:42 -0500 > To: cctalk at classiccmp.org > > >Pictures from the Smithsonian > http://users.starpower.net/dj.taylor/Vax1.JPG > > VAX MINICOMPUTER > > Digital Equipment Corporation's VAX minicomputer, first introduced > in 1976, provided enough processing power for complex design problems, > but at a much lower cost than had previously been available. This > meant that individuals engineers could have the fill use of a > computer without having to share it with their colleagues. The VAX > became the workhorse or aerospace engineering. The model displayed > here, a MicroVAX II was introduced in 1985. > > >Museum people! Oh well! They can obviously read, but cannot understand. >Hello?? The label says its a *MICRO*VAX, and if its a uVAX, then >its not a mini. Also, calling the baby-sized uVAX a mini gives >visitors who may have never seen a mini-computer the wrong idea as to >what a mini-computer looks like. Sure I'll accept that its *compatible* >with a VAX (I'll even ignore the minor business of emulating a small >part of the instruction set :-), but is not a VAX. Get over it. Like Antonio said, its a VAX, one archetecture multiple implmentations that act the same. The fact that the VAX ranged from the .5 cu/Ft MicroVAX2000 to the 9000 false floor heavyweight is relevent. If the mini thing were real it's actually a "superminicomputer". But if size is a factor then the VAX 9000 was anything but mini. We didn't call the 9000 a mainframe but it was huge for it's time. Allison

18 years, 8 months

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test-drb November 2005