Description:
The trusty old PDP 8.
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8 restoration update 20091123
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Over the weekend we attempted to align the core using the setup procedure. It didn't work out all that well and I am not sure why. We ended up putting all the settings back to the values that we had measured when it was working and now it will run the memory checkerboard test for as long as I am willing to run it. At least a... more »
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DCA vs DEP
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One of the key decisions made by the architects of the 8 was the Deposit Clear Accumulator instruction instead of a simple deposit where the accumulator is not cleared. It has never been clear to me that this was a wise decision because an extremely common operation is a DCA followed immediatly by a TAD to get the data back into the AC.... more »
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A Flight Of Fancy
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What might be obtained with the PDP8-E instruction set if we did no more than to increase the size of the memory reference from 7 bits by 20 bits to make it a 32-bit instruction set, but otherwise made no extensions to the Instruction Set? 2^27 is, subject to typos, 134,217,728. This would of course be a word count, giving an effective memory size... more »
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classiccmp.org
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I've been trying to get subscribed to the lists on classiccmp.org for a long time. The demon says that it is awaiting approval from the moderator. I assume the moderator has fallen into a black hole, or something. Is there a sneak path to to getting subscribed? Rob Doyle
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TU56 field strip
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I was given a "rough" TU56 and I’m in the process of restoring it. It really looked worse than it is. Strip-down wasn't too bad - hardest part was releasing the Mate N'Lock connectors for the motor harnesses deep inside the cabinet. Everything came apart easily and the motors all turn freely so I'm pretty optimistic about getting it running. Now... more »
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Small Computer Handbook 1973
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Is there any value in "pdp8/e pdp8/m & pdp8/f small computer handbook" of 1973? It's full of pictures about how computers are designed and made but which seem to bear no resemblance to today's products
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8 Restoration progress
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I don't know if there are people interested or not but I find I have a desire to talk about the progress we are making on getting it going again. This last week we made pretty good progress. By we I mean Warren Stearns, who also is a lover of old dusty computers, and myself. We both used this particular computer in college back in the 1970's. I... more »
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40 year old PDP-8
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A friend of mine who likes dusty old computers has been helping me get my Straight 8 running again. For the last couple of months it has been one thing after another going wrong. Over the weekend we were running a program we wrote to diagnose a JMS problem that was driving us crazy. Sometimes, it would set the return address to the address... more »
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50Hz vs. 60Hz?
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Folks, I'd appreciate some thoughts in general, and on some specific cases, on using 50Hz DEC equipment on 60Hz power, since I've started processsing and restoring a large quantity of DEC equipment I've brought over from my UK storage to the USA: 1. Thinking about old DEC logic power supplies in general (pdp-8, -11, -12, -15... more »
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