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  • jackrubin's Avatar
    Today, 05:32 AM
    jackrubin replied to a thread Unknown DEC Part in DEC
    Shipping for just the backplane shouldn't be too bad - small items below 4 pounds can go relatively reasonably by USPS First Class International.
    7 replies | 170 view(s)
  • jackrubin's Avatar
    Yesterday, 07:01 PM
    jackrubin replied to a thread Extended Bootloader Blues in DEC
    Well, the ghost came back, but I think it is now well and truly squashed. Earlier this week, the Computerarium was honored with a visit from a...
    21 replies | 795 view(s)
  • jackrubin's Avatar
    Yesterday, 06:49 AM
    I'm soldering in my sockets, but then I'm a belt-and-suspenders kind of guy.
    163 replies | 13871 view(s)
  • jackrubin's Avatar
    July 6th, 2019, 01:54 PM
    jackrubin replied to a thread New to me PDP-11/53 in DEC
    Mike - be careful with that QBUS stuff - it just works.
    7 replies | 292 view(s)
  • jackrubin's Avatar
    July 6th, 2019, 12:37 PM
    jackrubin replied to a thread Extended Bootloader Blues in DEC
    @Roland - Mike Zahorik seems to be using a combo board without any problems, but I don't know his exact setup. I certainly understand the long trace...
    21 replies | 795 view(s)
  • jackrubin's Avatar
    July 5th, 2019, 03:35 PM
    jackrubin replied to a thread Extended Bootloader Blues in DEC
    C10 is in place on both boards and didn't seem to stop the glitching. I installed the filter cap (across R_SW, not SW_RUN as I first wrote) directly...
    21 replies | 795 view(s)
  • jackrubin's Avatar
    July 5th, 2019, 03:34 PM
    jackrubin replied to a thread Extended Bootloader Blues in DEC
    I just tried the first (unmodified) Boot+Mem card with the machine closed (no cover) and the lab lights off. It ran the Accumulator Increment test...
    21 replies | 795 view(s)
  • jackrubin's Avatar
    July 5th, 2019, 02:23 PM
    jackrubin replied to a thread Extended Bootloader Blues in DEC
    I just shut the machine off - Accumulator Increment ran for over 1 1/2 hours.
    21 replies | 795 view(s)
  • jackrubin's Avatar
    July 5th, 2019, 01:38 PM
    jackrubin replied to a thread Extended Bootloader Blues in DEC
    At Roland's suggestion, I installed a 1 uF capacitor between pin 15 (SW_RUN) and pin 8 (GND) on the Atmega to reduce the chance of EMI glitches. I...
    21 replies | 795 view(s)
  • jackrubin's Avatar
    July 5th, 2019, 07:25 AM
    jackrubin replied to a thread Extended Bootloader Blues in DEC
    Moving along slowly, I built my second Mem+Bootloader card last week and brought it out to the Computerarium for testing. It exhibited the same...
    21 replies | 795 view(s)
  • jackrubin's Avatar
    July 2nd, 2019, 03:42 PM
    jackrubin replied to a thread Atex PDP-11/34 in DEC
    Nick, Is the machine in San Jose or Vancouver? If it's in San Jose and you haven't made much progress over the next few weeks, why not bring...
    24 replies | 888 view(s)
  • jackrubin's Avatar
    June 30th, 2019, 06:12 AM
    I'm pretty sure daver2 already pointed to them, but they're buried in the old N8VEM wiki -...
    163 replies | 13871 view(s)
  • jackrubin's Avatar
    June 29th, 2019, 06:27 PM
    Caveat Emptor - there are _FOUR_ editions of "The Art of Digital Design"! Here's more than you'll ever need to know about the various editions: ...
    163 replies | 13871 view(s)
  • jackrubin's Avatar
    June 27th, 2019, 06:43 AM
    With boards in hand and parts on order, I've been reviewing Winkel and Prosser (1980; they switched the name order for the 1987 second edition) and...
    163 replies | 13871 view(s)
  • jackrubin's Avatar
    June 25th, 2019, 09:36 AM
    jackrubin replied to a thread VC8E point plot 74xx replica in DEC
    Here's a link to my folder on the KV8I, a bit more elaborate implementation using the TEK 611 but also supporting a joystick. The cabling and 611...
    20 replies | 1258 view(s)
  • jackrubin's Avatar
    June 24th, 2019, 05:01 AM
    jackrubin replied to a thread VC8E point plot 74xx replica in DEC
    Re the M8650, I've got several of them with DL1 (30 ns delay line) either broken off or missing altogether; I expect others do as well. A small...
    20 replies | 1258 view(s)
  • jackrubin's Avatar
    June 23rd, 2019, 06:31 AM
    jackrubin replied to a thread PDP-9 at the RICM in DEC
    What bulbs does the panel require? Were you able to find present-day replacements or are you using old spares? I've got a couple of TC02 panels to...
    62 replies | 7839 view(s)
  • jackrubin's Avatar
    June 22nd, 2019, 07:58 PM
    I was actually looking at the MC8/I, which uses a 3-bit IF/DF for the full 32K words of memory on the 8/I, rather than the MC8/L. Either way, you're...
    163 replies | 13871 view(s)
  • jackrubin's Avatar
    June 22nd, 2019, 12:03 PM
    jackrubin replied to a thread VC8E point plot 74xx replica in DEC
    I expect there's a whole lot of people who would say we're all 4 bits short of a word. Keep calm and carry on (at least 'til October 31) ...
    20 replies | 1258 view(s)
  • jackrubin's Avatar
    June 20th, 2019, 11:39 AM
    A member of another mailing list pointed out this 24K memory expansion box for the 8/I -...
    163 replies | 13871 view(s)
  • jackrubin's Avatar
    June 20th, 2019, 06:23 AM
    The boards look great, but I'd still vote for SMD bypass caps. 0805 parts are easy and a nice way to transition toward that technology. Maybe rev 2?...
    163 replies | 13871 view(s)
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About alex-h89

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About alex-h89
Location:
SE Pennsylvania
Interests:
Heathkit H8,H89 and H11
Occupation:
retired

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