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  • daver2's Avatar
    Today, 11:31 AM
    daver2 replied to a thread Build your own PDP 8I, Part 4.. in DEC
    >>> Dave, are you incrementally updating the construction/assembly manual on your Google Drive? Or should I wait a bit to get the benefit of your...
    175 replies | 14301 view(s)
  • daver2's Avatar
    Today, 10:23 AM
    daver2 replied to a thread Build your own PDP 8I, Part 4.. in DEC
    >>> Dave, are you incrementally updating the construction/assembly manual on your Google Drive? Or should I wait a bit to get the benefit of your...
    175 replies | 14301 view(s)
  • daver2's Avatar
    Today, 06:44 AM
    daver2 replied to a thread Build your own PDP 8I, Part 4.. in DEC
    This is based upon what I have seen on the original at...
    175 replies | 14301 view(s)
  • daver2's Avatar
    Today, 02:15 AM
    daver2 replied to a thread Build your own PDP 8I, Part 4.. in DEC
    I have made a start on my board also. I have the 'disadvantage' in that I am having to write the construction/assembly manual as I go... ...
    175 replies | 14301 view(s)
  • daver2's Avatar
    July 20th, 2019, 01:00 AM
    daver2 replied to a thread Unknown DEC Part in DEC
    I have been looking for something like this for a while for my LSI-11/02 cards. I suspect shipping to the UK would be prohibitively expensive...
    7 replies | 204 view(s)
  • daver2's Avatar
    July 16th, 2019, 02:16 AM
    Thanks for the 'bump'. I completely missed your post. Been busy over in DEC PDP-8 land recently (although I did pull my MK14 stuff out of the storage...
    82 replies | 19032 view(s)
  • daver2's Avatar
    July 15th, 2019, 04:13 AM
    daver2 replied to a thread Build your own PDP 8I, Part 4.. in DEC
    >>> This Explains why my friend is using the 2N7000 in numerous places , I think it is for LED display purposes, on the 8080 Diode Transistor unit.....
    175 replies | 14301 view(s)
  • daver2's Avatar
    July 14th, 2019, 11:56 AM
    Nice detective work! Dave
    22 replies | 467 view(s)
  • daver2's Avatar
    July 14th, 2019, 11:40 AM
    daver2 replied to a thread Build your own PDP 8I, Part 4.. in DEC
    Been thinking about the front panel issue. Some further thoughts: The LD12 is based upon a PDP-8/I not a PDP-8/L. I got my letters and numbers...
    175 replies | 14301 view(s)
  • daver2's Avatar
    July 14th, 2019, 08:07 AM
    You say above that you replaced C51 with an electrolytic. The parts list calls for a low leakage electrolytic - or a tantalum. If the capacitor is...
    31 replies | 613 view(s)
  • daver2's Avatar
    July 12th, 2019, 07:23 AM
    daver2 replied to a thread Build your own PDP 8I, Part 4.. in DEC
    smp: Will send you the KiCAD files when I get a few minutes. It is unlikely to be this weekend though. We may have to do this 'incrementally' as I...
    175 replies | 14301 view(s)
  • daver2's Avatar
    July 10th, 2019, 12:35 AM
    Based upon your last post I would check the following: R15 (1k pull-up to +5V). The 7407/7417 are open collector devices. So if this resistor is...
    31 replies | 613 view(s)
  • daver2's Avatar
    July 9th, 2019, 09:42 AM
    If the reset circuitry doesn't work - then there is no chance of the PET working. Solder a normally open pushbutton either across C51 - or between...
    31 replies | 613 view(s)
  • daver2's Avatar
    July 9th, 2019, 06:09 AM
    Monty, I like your optimism :-)! I am not particularly bothered about the microcoded instructions to be honest. Since I am emulating the...
    7 replies | 136 view(s)
  • daver2's Avatar
    July 9th, 2019, 12:39 AM
    As Frank has pointed out, the MK36000 device is not as simple as potentially other (EP)ROMS are becuase of the address latch. It is all down to...
    22 replies | 467 view(s)
  • daver2's Avatar
    July 8th, 2019, 10:26 PM
    Nice going (again) Monty. I was just re-reading the thread where you introduced yourself to VCFED. What progress you have made with all this Tek...
    7 replies | 136 view(s)
  • daver2's Avatar
    July 8th, 2019, 11:20 AM
    Doing a bit more digging. I have used V5.1 firmware and V5 microcode in my 4052 emulator. The ROM code starts at 79F3 for V5.1 firmware. The...
    22 replies | 467 view(s)
  • daver2's Avatar
    July 8th, 2019, 08:35 AM
    I don't think the PET ROMs should be accessing the upper bank of 16K RAM unless you have written some sort of (BASIC) program to do that. As a...
    31 replies | 613 view(s)
  • daver2's Avatar
    July 8th, 2019, 06:02 AM
    Maybe a good idea to read this thread http://www.vcfed.org/forum/showthread.php?18995-Saving-ROM-data-from-Tek-4052. There is a lot (and I mean a...
    22 replies | 467 view(s)
  • daver2's Avatar
    July 8th, 2019, 05:11 AM
    Found Jos's 4052/4054 diagnostic ROM pack thread at http://www.vcfed.org/forum/showthread.php?63025-Tektronix-4052-54-diagnostic-ROM-pack-remade. ...
    22 replies | 467 view(s)
  • daver2's Avatar
    July 7th, 2019, 10:45 PM
    Are you addressing RAM in the >16K range or not? If not, the upper RAM CAS line will not be activated. The ROMs will be constantly accessing...
    31 replies | 613 view(s)
  • daver2's Avatar
    July 7th, 2019, 10:41 PM
    Hi, About to run off to work, but will get back to you at some point (or some of the other Tekies will)! If you hunt around on VCFED you will...
    22 replies | 467 view(s)
  • daver2's Avatar
    July 3rd, 2019, 10:04 PM
    Start here with the documentation: http://www.bitsavers.org/pdf/osborne/executive/. Do you have any test equipment (e.g. multimeter, logic probe...
    3 replies | 112 view(s)
  • daver2's Avatar
    July 2nd, 2019, 12:42 PM
    Is the code for your Sim4-01 EPROMs on the web anywhere (or would you be willing to share them)? I might be interested in seeing if I can reconstruct...
    3 replies | 143 view(s)
  • daver2's Avatar
    July 2nd, 2019, 12:35 PM
    daver2 replied to a thread Atex PDP-11/34 in DEC
    The problem you have is that you have too many variables... It is no good just plugging things in and hoping a serial port will burst into life....
    24 replies | 897 view(s)
  • daver2's Avatar
    July 1st, 2019, 05:36 AM
    I read T701 here http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/pet/2001N/321446.gif Dave
    46 replies | 921 view(s)
  • daver2's Avatar
    July 1st, 2019, 12:29 AM
    daver2 replied to a thread Atex PDP-11/34 in DEC
    Of course, the other 'simple' way of looking at this is "is there a cable/connector anywhere that came with the equipment that looks like it plugs...
    24 replies | 897 view(s)
  • daver2's Avatar
    June 30th, 2019, 11:09 PM
    daver2 replied to a thread Atex PDP-11/34 in DEC
    Excellent, The 1489 is the receiver, but I would expect a 1488 transmitter (if it was 'true' RS232). It may not be of course. I would next use...
    24 replies | 897 view(s)
  • daver2's Avatar
    June 30th, 2019, 02:22 PM
    40 column non-CRTC is fine - it works OK with that. The table that programs the CRTC is right at the beginning of the EPROM (apart from an initial...
    46 replies | 921 view(s)
  • daver2's Avatar
    June 30th, 2019, 01:44 PM
    Yep, my program initialises the CRTC (in default 80 column mode) - so it should work with both non CRTC and CRTC PETs (providing they have 80 column...
    46 replies | 921 view(s)
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