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  • daver2's Avatar
    Today, 10:11 AM
    daver2 replied to a thread PDP-11 Multi-User Game in DEC
    The source for Essex University MUD1 on a PDP-10 written in BCPL is available at https://github.com/PDP-10/MUD1. I modified the source code for an...
    3 replies | 144 view(s)
  • daver2's Avatar
    August 13th, 2017, 12:59 AM
    Either remove the CPU and make a small adapter board to decode ROM fxxx and operate the /NOROM pin to disable the onboard ROM(s) or plug a ROM and...
    29 replies | 775 view(s)
  • daver2's Avatar
    August 10th, 2017, 08:56 AM
    DM and SN devices 'should' be the same - they just indicate different manufacturers. SN is Texas Instruments. Functionally they are the same device....
    29 replies | 775 view(s)
  • daver2's Avatar
    August 10th, 2017, 08:47 AM
    daver2 replied to a thread New old guy in Introductions
    Welcome to VCFED. Can I suggest you fill in your location. You never know, some of us could live near you? Dave
    3 replies | 193 view(s)
  • daver2's Avatar
    August 9th, 2017, 11:14 AM
    How serious are you about wanting to get your PET to work? Do you have any electronics experience? Can you read an electronics schematic? ...
    5 replies | 183 view(s)
  • daver2's Avatar
    August 9th, 2017, 10:56 AM
    daver2 replied to a thread Altair 8800 Information in S-100
    See if you can find a Variac - that would be my recommendation. Those resources are the primary 'goto' ones we all know about and very much...
    19 replies | 580 view(s)
  • daver2's Avatar
    August 9th, 2017, 09:32 AM
    By the sound of it - Grant's website Z80 design will be right up your street then... And you have pre-built boot ROMS (including a simple monitor and...
    17 replies | 506 view(s)
  • daver2's Avatar
    August 9th, 2017, 09:20 AM
    daver2 replied to a thread Tek 4051 startup sequence in Other
    Not quite what you wanted (it is a 4052 not a 4051) but I think the same thing applies. See https://www.youtube.com/watch?v=EXNXIRzI0xw You can...
    2 replies | 107 view(s)
  • daver2's Avatar
    August 9th, 2017, 07:09 AM
    daver2 replied to a thread Tek 4051 startup sequence in Other
    I have seen some Youtube videos - but it will take me a short while to get a link for you (I am just on my way home from work at the moment and we...
    2 replies | 107 view(s)
  • daver2's Avatar
    August 8th, 2017, 12:07 PM
    Here is a useful reference http://www.msxarchive.nl/pub/msx/mirrors/hanso/datasheets/chipsz80leventhal3.pdf. Dave
    17 replies | 506 view(s)
  • daver2's Avatar
    August 8th, 2017, 11:29 AM
    daver2 replied to a thread Altair 8800 Information in S-100
    The first thing to do is document EXACTLY what you have got. What connects to what and which way round. etc. Each of the cards should/will have...
    19 replies | 580 view(s)
  • daver2's Avatar
    August 8th, 2017, 10:51 AM
    I would try a few drops of isopropyl alcohol (or similar) to clean the heads a bit better than a disk cleaner may do (see something like...
    6 replies | 228 view(s)
  • daver2's Avatar
    August 8th, 2017, 10:30 AM
    What is your definition of 'build'? At the card or component level? if at the component level - I would suggest checking out Grant's excellent...
    17 replies | 506 view(s)
  • daver2's Avatar
    August 8th, 2017, 10:23 AM
    +1 for the suggestions of both Chuck and Dave. The other thing to consider is the media you are using. Is it old and ancient and failing? Dave
    6 replies | 228 view(s)
  • daver2's Avatar
    August 7th, 2017, 04:25 AM
    daver2 replied to a thread Im new here in Introductions
    Welcome too! The mods take a little while - but they get there (overworked and under paid at 0/hr). We are a really helpful bunch here - so it is...
    8 replies | 226 view(s)
  • daver2's Avatar
    August 7th, 2017, 04:12 AM
    You can use FOR/NEXT loops in a direct statement - providing you use a multi-statement line with the statements separated by ':' (which is the case)....
    29 replies | 805 view(s)
  • daver2's Avatar
    August 4th, 2017, 09:49 AM
    Hi Mark and welcome to VCFED. The key bit of information you have omitted is - where do you live? If you are in the UK - I have a Toshiba...
    16 replies | 454 view(s)
  • daver2's Avatar
    July 31st, 2017, 10:27 AM
    daver2 replied to a thread PDP 11/45, Part 6 in DEC
    Just a thought before I go out for the evening. You have run the tests detailed in section 2.5.3.1 on page 2-9 onwards of...
    103 replies | 3591 view(s)
  • daver2's Avatar
    July 31st, 2017, 07:13 AM
    daver2 replied to a thread PDP 11/45, Part 6 in DEC
    Yes, you are making sense. In my opinion you can't (easily) use the FLOW diagrams to do what you want. I would look at the two block diagrams on...
    103 replies | 3591 view(s)
  • daver2's Avatar
    July 30th, 2017, 08:06 AM
    daver2 replied to a thread PDP 11/45, Part 6 in DEC
    >>> Yes, it might be about Wednesday before I can get to things.. No problem - no one is in any hurry... >>> I was thinking of more than the...
    103 replies | 3591 view(s)
  • daver2's Avatar
    July 29th, 2017, 11:47 PM
    daver2 replied to a thread PDP 11/45, Part 6 in DEC
    Marty, Before you get distracted, work through the logic of what I had previously posted to ensure you are getting the correct pulses and levels...
    103 replies | 3591 view(s)
  • daver2's Avatar
    July 28th, 2017, 09:06 AM
    daver2 replied to a thread PDP 11/45, Part 6 in DEC
    Just think - DEC could have made this difficult if they wanted to :-)!!! More eyes are always good... Right, I am off for a barbecue in the...
    103 replies | 3591 view(s)
  • daver2's Avatar
    July 28th, 2017, 08:59 AM
    daver2 replied to a thread PDP 11/45, Part 6 in DEC
    Fritz is sort of right... I misread "UBCF START (1) H" as "UBCF START H". "UBCF START H" comes from the <START> key. "UBCF START (1) H" comes from...
    103 replies | 3591 view(s)
  • daver2's Avatar
    July 28th, 2017, 05:13 AM
    daver2 replied to a thread PDP 11/45, Part 6 in DEC
    >>> I will be busy on and off today, so it might a little slow going.. No problem. My wife has an 'event' for me to attend tonight - so I may not...
    103 replies | 3591 view(s)
  • daver2's Avatar
    July 28th, 2017, 02:43 AM
    daver2 replied to a thread Saving ROM data from Tek 4052 in Other
    I shall have a look tomorrow. I am unable to access file sharing websites from work and my wife has an 'evening activity out' planned for me tonight!...
    61 replies | 4557 view(s)
  • daver2's Avatar
    July 28th, 2017, 02:29 AM
    daver2 replied to a thread PDP 11/45, Part 6 in DEC
    Marty, Thanks for the update. So something is awry on schematic UBCE. Can I propose the following: E31 pin 2 - there should be a high going...
    103 replies | 3591 view(s)
  • daver2's Avatar
    July 27th, 2017, 12:48 PM
    daver2 replied to a thread PDP 11/45, Part 6 in DEC
    That sounds like a plan - just work your way backwards and see what is wrong. From what I remember the logic isn't too difficult. Night time in...
    103 replies | 3591 view(s)
  • daver2's Avatar
    July 27th, 2017, 12:20 PM
    daver2 replied to a thread PDP 11/45, Part 6 in DEC
    I think there should be a pulse from what I have seen from the schematics. What is the state of the Q and /Q outputs on E37 pins 8 and 9 after you...
    103 replies | 3591 view(s)
  • daver2's Avatar
    July 27th, 2017, 11:28 AM
    daver2 replied to a thread PDP 11/45, Part 6 in DEC
    Load our test program. Try and <START> the program and see if you get a low going pulse on E37 pin 13 when you hit <START>. Don't bother single...
    103 replies | 3591 view(s)
  • daver2's Avatar
    July 27th, 2017, 02:33 AM
    daver2 replied to a thread PDP 11/45, Part 6 in DEC
    I think I have a strategy! Things are pointing to the flop-flop E37 pins 8 and 9 on drawing TMCA (upper left-hand corner of the drawing). I...
    103 replies | 3591 view(s)
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