back to article DEC: The best of systems, the worst of systems

Which were the greatest DEC computers and why? Which were the worst - and why? Everyone has their own definition of greatest and worst, and exemplars of each, but I'm looking at the machines that had the most or the least influence. Since DEC under Olsen got a lot of things right, it's quicker and easier starting from the …

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  1. dreamingspire
    Happy

    Extra bit in the middle

    The Elliott 503 also had an extra bit in the middle: 39 bit word holding 2 instructions, the bit in the middle being a flag bit that if set caused the result of the first instruction to be a modifier for the 2nd instr.

    Which takes me to the spoof about ICL New Range: that it would have a 49 bit word (8 x 6 to emulate 1900, or 6 x 8 for NR native mode), plus a spare bit. "What is the spare bit for?" was the core of the spoof. Two of us created it, and it ran quite some distance.

  2. OldMan

    PDP-8e User

    I joined DEC in September 1969 to work on peripheral product design. I got to have my own PDP-8e in my office. What a thrill to have my own personal computer. I think it had only 4K of core memory. My first job assignment was to design a paper tape punch mechanism for the LA30 as it was planned to be a replacement for a KSR33 teletype machine. I used the PDP-8e to run a dynamic simulation program that I wrote in FOCAL for the punch solenoid designs I created. With the limited memory I had to print each computed result as there was insufficient memory to store all of the results. Before I completed my design efforts the paper tape punch feature was eliminated from the LA30. I got to keep the PDP-8e for future design projects.

  3. Hoofhearted
    Pint

    Too many war stories

    After 27 years in Field Service I've seen every thing from the first an only 8K PDP-5 in the world,(we had to add a extra SWR switch to address the upper 4K) to a CSS designed 11/05 machine that made Michelob bottles. For me the 11/45/55/70 were some of the best PDP's ever made. The great thing about the PDP was that when you went to a site that you had never been to before. You could never tell what might be hanging off the Unibus. Pumping machine language into the switch register to massage the periph's was such fun. As it was said then, I could 12737 with the best of them. Everything on the system could be gotten to from the SWReg, PDP8's were okay, but a bit slow. VAX780's were a dream come true for FS people that had logical snap to be able to fix them. Alpha's were really a gas. We had a saying "Intel, Alpha inside" those old Pentiums would burn your finger until Intel got DEC to tell how to cool them down.

    For a few years I was support for the RA81, spent a pile of Ken's money fixing the original design. Dropped 67 Mil swapping HDA's with FCO13, but I did manage to kill the ECC epidemic with a single piece of wire. The Ground Strap FCO eliminated gound noise on the pre-amps from 40 Miilvolts to zero, which made for a nice reference.

    1. Steve X

      You could never tell what might be hanging off the Unibus

      Nice cue, and since no-one else has mentioned "Always mount a scratch monkey" yet...

      http://edp.org/monkey.htm

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