test-drb

test-drb@ccmp.vtda.org

101090 discussions

by shadoooo＠gmail.com

Hello, I have a VT100 to repair, I need a 16-16463-00 flyback transformer, but these seem to be unavailable... Anyone has to sell? Thanks Andrea

12 years, 1 month

cctech Digest, Vol 131, Issue 26

by michael.99.thompson＠gmail.com

> From: Kevin Keith <krfkeith at gmail.com> > Date: Thu, 17 Jul 2014 13:51:56 -0600 > Subject: Re: Yet Another FPGA VAX Discussion > Ha! > > "[Futurebus] intended to replace all local bus connections in a > computer, including the CPU, memory, plug-in cards and even, to some > extent, LAN links between machines." > > How accurate is that statement? There doesn't appear to be any citation. > > -- > Thanks, > Kevin At the time it was developed Futurebus+ was probably the most advanced and highest performance bus. It had very advanced protocols that did a great job of handling distributed cache coherency, and a very nice distributed priority resolution circuitry. DEC could have build a complete VAX or Alpha on Futurebus+ and made a very high performance system. SCI (Scalable Coherent Interface) would be the best choice for interconnecting Futurebus+ systems. Unfortunately the NAVY's NGCR program, that was one of the big target markets for Futurebus+, was defunded and support for Futurebus+ evaporated. High speed serial buses were also getting fast enough to be competitive with parallel buses, and much easier to implement than a 64/128/256 bit wide bus. -- Michael Thompson

12 years, 1 month

Any US IBM System 34 or 36 owners out there?

by cclist＠sydex.com

I received a call from a gentleman who'd like to get a listing of the contents of a couple of System 34 floppy magazines. Seems he wrote some business applications a years ago and would like to have a printed record of the source. If you are willing to tackle this (for money that you'd negotiate for, of couse), drop me a line and I'll hook you up. --Chuck P.S. I do know that you can open the magazines and retrieve the floppies one by one, but if you've got the IBM gear, it would be so much simpler.

12 years, 1 month

Yet Another FPGA VAX Discussion

by michael.99.thompson＠gmail.com

> From: Paul Koning <paulkoning at comcast.net> > Date: Wed, 16 Jul 2014 17:33:02 -0400 > Subject: Re: Yet Another FPGA VAX Discussion > > Also Futurebus. Or did that never make it out the door? I remember a pile of work on that. Very strange bus, not well named. :-) > > paul I worked on the original IEEE-896 Futurebus standard and the updated Futurebus+ that DEC used. I think that it was used on the VAX 10000 and 7000. They made the DWLAA Futurebus+ bridge and the DEFAA-YA FDDI board for Futurebus+. I have the DEC tutorial book on Futurebus+. -- Michael Thompson

12 years, 1 month

RetroComputing talk at CircleCityCon

by christian_liendo＠yahoo.com

One person's take on retro computing older Unix machines.? https://www.youtube.com/watch?v=5qkuRiDS-gU

12 years, 1 month

ThinkPad 860 / 850 1.2GB HD

by BHuntsman＠mail2.cu-portland.edu

Anyone here have an extra/parts machine ThinkPad 860 or 850 with a working 1.2GB hard drive in the caddy? I'm having terrible luck finding one. So I'll throw out a bounty :) I'll offer $100 for just the drive and caddy... Thanks in advance! -Ben

12 years, 1 month

Recent prices for Vintage computers ( yes I know this is a COW (can of worms) )

by earl＠baugh.org

I've been helping in some restorations recently (both my own, and someone I know's Sun 1...) and one of the questions that have come up is valuation (say for insurance, etc, or acquiring another system...) Is there some sort of collected list of values of some of vintage machines that have sold, either ebay, privately, auction, etc.? I know that something is worth only what someone will pay for it, but for insurance purposes at least you'd need some sort of benchmark to give to the insurance company... I know you don't get a good valuation if you let them do it... Thanks. Earl

12 years, 1 month

Recent prices for Vintage computers ( yes I know this is a COW (can of worms) )

by cctech＠beyondthepale.ie

> >I've been helping in some restorations recently (both my own, and someone I >know's Sun 1...) and one of the questions >that have come up is valuation (say for insurance, etc, or acquiring >another system...) > >Is there some sort of collected list of values of some of vintage machines >that have sold, either ebay, privately, >auction, etc.? > >I know that something is worth only what someone will pay for it, but for >insurance purposes at least you'd need >some sort of benchmark to give to the insurance company... I know you don't >get a good valuation if you let them do it... > When considering insurance, I think the questions to ask are if the system is a total loss, would it be possible to replace it with an acceptable equivelant and if so, how much would it cost to do this. However difficult this is to calculate in a way acceptable to the insurance company now, bear in mind that in the event of a claim, they are probably going to go over values with a fine toothed comb and by then, costs and availablilty may well have changed. If it isn't possible to replace it, then there is no point in insuring it. Someone who regards classic computers as some sort of investment would probably disagree but I don't think that's what we are about here. Museums would probably disagree for different reasons. Regards, Peter Coghlan.

12 years, 1 month

PDP-8/S Incompatibilities......

by lbickley＠bickleywest.com

I've had my PDP-8/S up and running for some time - but have recently experienced failures using some PDP-8 software. My 8/S passes all the DEC diagnostics - and it runs FOCAL-69 and 71 perfectly. So I decided to track down what was causing some programs to fail - and I discovered that the problem is PDP-8/S incompatibilities. PDP-8/S "Reality" ----------------- The PDP-8/S User Manual lies! It makes the following claim regarding Group 1 Operate Instructions: "The only restriction on combining OPR 1 (Group 1) operations within one instruction, other than logical conflicts, is that a rotate operation (bits 8, 9 or 10) may not be combined with the increment AC operation (bit 11) since they are executed during the same bit times." I decided to test that claim on my PDP-8/S and got the following results (via single stepping through the test program below.) The "8/S" column is Link AC contents (L AAAA): *200 Page 1 1 0200 *200 2 /AC 8/S NOTES 3 00200 7200 CLA /0 0 0000 4 00201 7201 CLA IAC /1 0 0001 5 00202 7326 CLA CLL CML RTL /2 0 0002 6 00203 7325 CLA CLL CML IAC RAL /3 1 0003 8/I AND UP 7 00204 7307 CLA CLL IAC RTL /4 1 0001 8/I AND UP 8 00205 7327 CLA CLL CML IAC RTL /6 1 0003 8/I AND UP 9 00206 7215 CLA IAC RAL RAR /10 1 0003 6120 10 00207 7203 CLA IAC BSW /100 1 0001 8/E AND UP 11 00210 7332 CLA CLL CML RTR /2000 0 2000 12 00211 7354 CLA CLL CMA RAR RAL /3776 1 7777 8/I OR 8/L 13 00212 7350 CLA CLL CMA RAR /3777 1 7777 14 00213 7330 CLA CLL CML RAR /4000 0 4000 15 00214 7352 CLA CLL CMA RTR /5777 1 7777 16 00215 7333 CLA CLL CML IAC RTR /6000 1 0003 8/I AND UP 17 00216 7346 CLA CLL CMA RTL /7775 1 7777 18 00217 7344 CLA CLL CMA RAL /7776 1 7777 19 00220 7240 CLA CMA /7777 ? 7777 20 00221 7402 HLT 21 $ No detected errors No links generated Note that all of the CMA shift instructions failed - even though the test (from Programming Languages) thought they should work in pre-8/I machines. At first I thought my PDP-8/S was failing - until I found the following from the PDP-8/S FAQ (What is a PDP-8/S?): "Compatibility: The core of the PDP-8 instruction set is present, but there are a sufficient number of incompatibilities that, as with the PDP-5, many otherwise portable "Family of 8" programs will not run on the PDP-8/S. Perhaps the worst incompatibility is that the Group 1 OPR instruction CMA cannot be combined with any of the rotate instructions; as with the PDP-8, IAC also cannot be combined with rotate." I decided to understand WHY this happens - and the answer is in the PDP-8/S Maintenance Manual and the PDP-8/S schematics. I've abreviated the sequence of execution below. (The "Ax" references are bit timimg): Group 1 Instruction Sequencing ------------------------------ Fetch ----- A12 Set or Clear Link, Clear AC per instruction Execute ------- A00 For right rotation (A00-01), shift AC+L together once or twice per instruction A(00-11) IAC: Adds one to AC CMA: Complements the AC IAC*CMA: Complement and add one to AC Left Rotate: AC+L shifted right 11 or 12 times per instruction A12 IAC: Complements L on overflow (CMA appears in gating, but has no effect) As can be seen, while the system clears the AC and clears or sets the Link during Fetch - it rotates right BEFORE complementing the AC! It also attempts to execute a complement of the AC at the SAME TIME as a left rotate - which simply does not work! Finally, just to verify the correctness of the test program, I single stepped it on my PDP-8/E and got the same results as the SIMH trace below: SIMH PDP8 Trace of the above: ----------------------------- sim> sh cpu history PC L AC MQ ea IR 00200 1 7777 0000 CLA 00201 1 0000 0000 CLA IAC 00202 1 0001 0000 CLA CLL CML RTL 00203 0 0002 0000 CLA CLL CML IAC RAL 00204 0 0003 0000 CLA CLL IAC RTL 00205 0 0004 0000 CLA CLL CML IAC RTL 00206 0 0006 0000 CLA IAC RAL RAR 00207 0 0001 0000 CLA IAC BSW 00210 0 0100 0000 CLA CLL CML RTR 00211 0 2000 0000 CLA CLL CMA RAL RAR 00212 0 7354 0000 CLA CLL CMA RAR 00213 1 3777 0000 CLA CLL CML RAR 00214 0 4000 0000 CLA CLL CMA RTR 00215 1 5777 0000 CLA CLL CML IAC RTR 00216 0 6000 0000 CLA CLL CMA RTL 00217 1 7775 0000 CLA CLL CMA RAL 00220 1 7776 0000 STA 00221 1 7777 0000 HLT sim> Cheers, Lyle -- Bickley Consulting West Inc. http://bickleywest.com "Black holes are where God is dividing by zero"

12 years, 1 month

Recent prices for Vintage computers

by billdeg＠buzz1.com

> Subject: Recent prices for Vintage computers ( yes I know this is a COW (can of worms) ) > Is there some sort of collected list of values of some of vintage machines that have sold, either ebay, privately, auction, etc.? > I know that something is worth only what someone will pay for it, but for insurance purposes at least you'd need some sort of benchmark to give to the insurance company... I know you don't get a good valuation if you let them do it... For insurance prices you need the replacement cost. Has to be documented. You need good photos of the item insured "before" and you need purchase receipts and/or documentation of a similar item on Ebay. Using Ebay is good because these tend to be retail prices. For oddball collectibles, which is what the insurance business considers a niche like vintage computers, you need a lot of documentation to back up your claims, bottom line. Also be sure your items have been stored at least 6 inches above the floor. I have a small policy with the expectation that I will not lose everything at once, and that it will be hard to get 100% of what I paid for anything. Forget about your labor. There is an older book by M Nadeau called "Collectible Microcomputers". The low prices are a reflection of the year the book was compiled, but the book helps establish a valuation trend, a point of reference in time. It would be nice if this were updated. Bill

12 years, 1 month

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