Image Map Image Map
Tab Content
  • daver2's Avatar
    Today, 10:51 AM
    daver2 replied to a thread D.R.E.A.M. 6800 Build in Other
    Bare PCBs arrived the other day. I am going to spend some time tomorrow ordering components I can see! I have designed a stackable PIA board that...
    63 replies | 4162 view(s)
  • daver2's Avatar
    March 20th, 2019, 10:55 PM
    daver2 replied to a thread Repair of a PET 4032 in Commodore
    As this is your first post, welcome to VCFED. I am way too far away from you (being in the UK) but you have come to the right place! Let's hope...
    4 replies | 79 view(s)
  • daver2's Avatar
    March 20th, 2019, 10:49 PM
    daver2 replied to a thread Help testing PDP-11/73 in DEC
    You shouldn't require any cards at all (other than the CPU and an external serial card if the CPU doesn't have one) to get ODT up and running. We did...
    7 replies | 163 view(s)
  • daver2's Avatar
    March 20th, 2019, 03:05 PM
    I thought he ha the same sense of humour as me :-). ave.
    6 replies | 71 view(s)
  • daver2's Avatar
    March 20th, 2019, 08:54 AM
    >>> And just to be clear, every other key on the boar works fine and comes up on the screen. It's just the one, so it has to be an issue with just...
    6 replies | 71 view(s)
  • daver2's Avatar
    March 19th, 2019, 11:44 PM
    +1 for Chuck's isolating transformer. Be safe! Dave
    16 replies | 221 view(s)
  • daver2's Avatar
    March 19th, 2019, 11:37 PM
    Hi, and welcome to VCFED (as this is your first post). There is a very long series of threads on fixing an O1 with a duff key. If you look at my...
    6 replies | 71 view(s)
  • daver2's Avatar
    March 18th, 2019, 04:05 PM
    >>> The Z80 was used in millions of CP/M computers. So it looks like an oddity for me that there is still no any CP/M version optimized for the...
    32 replies | 563 view(s)
  • daver2's Avatar
    March 18th, 2019, 12:15 AM
    daver2 replied to a thread Vintage years. in General Off Topic
    I sat on our company's Y2k committee and the numbers of equipment that failed the tests that we required for operation of our plant was quite large....
    7 replies | 153 view(s)
  • daver2's Avatar
    March 17th, 2019, 03:52 AM
    Hi Rob, Yes, I have learnt the hard way a few times that for a long or complex post you are better off editing your post outside of VCFED then...
    154 replies | 34305 view(s)
  • daver2's Avatar
    March 16th, 2019, 03:26 PM
    daver2 replied to a thread Nascom in Other
    I'll catch up with your posts tomorrow. Yes, the NASCOM 1 suffered from contention when accessing the video RAM at high speed (as you are doing)....
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 16th, 2019, 09:09 AM
    daver2 replied to a thread Nascom in Other
    Very interesting Mr. Spock... Having the 74S04 installed in IC9 is another modification to alleviate memory plague. I therefore suspect that...
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 16th, 2019, 05:34 AM
    daver2 replied to a thread Nascom in Other
    Thanks for the vote of confidence Ziloo... Yes, that part of the movie was an absolute classic moment! Debugging computer systems used to be my...
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 16th, 2019, 04:56 AM
    Well done, I was just thinking this morning on my walk that I hadn't heard back from you in a while. So, it was most likely the original and...
    77 replies | 4280 view(s)
  • daver2's Avatar
    March 16th, 2019, 04:16 AM
    daver2 replied to a thread Nascom in Other
    So, I can't see anything physically wrong with your RAM 'A' card scans. The 8K ROM BASIC upgrade seems to follow that as described - with the...
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 15th, 2019, 03:26 PM
    daver2 replied to a thread Nascom in Other
    I thought you were a bit quiet today... No problem, you need to prioritise your work! It is a good idea to scan the cards though. I have had a...
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 15th, 2019, 07:43 AM
    daver2 replied to a thread Nascom in Other
    The next thing to look at is the 4K and 16K decode logic on the RAM board. To do this, enter a very small program into memory via NAS-SYS and...
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 15th, 2019, 07:20 AM
    daver2 replied to a thread Nascom in Other
    Ok, so I have reacquainted myself with the schematics. The problem is unlikely to be the 81LS97s on the RAM board. The ROM and RAM have separate...
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 14th, 2019, 01:07 PM
    daver2 replied to a thread Nascom in Other
    81LS95 vs 81LS97 device. The 81LS97 is a dual 4-bit tristate buffer. It has two active low enable pins. Pin 1 enables the first half of the...
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 14th, 2019, 10:51 AM
    On a project I am currently working on - we have some wire-wrap configuration posts on one of the cards we are remanufacturing. The PCB assembly firm...
    154 replies | 34305 view(s)
  • daver2's Avatar
    March 14th, 2019, 08:23 AM
    daver2 replied to a thread Nascom in Other
    The 7402 is associated with the address decoding for the BASIC ROM. Thanks for the photographs - the wire links make complete sense to me - although...
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 12th, 2019, 08:42 AM
    Ditto for me. Dave
    16 replies | 462 view(s)
  • daver2's Avatar
    March 12th, 2019, 08:39 AM
    daver2 replied to a thread Nascom in Other
    Page 12 of https://80bus.co.uk.mirror.jloh.de/publications/magazines/INMC_news_5.pdf#page=13 describes the RAM A modification to add the 8K ROM BASIC...
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 12th, 2019, 08:27 AM
    daver2 replied to a thread Nascom in Other
    Documentation at https://80bus.co.uk.mirror.jloh.de/pages/nascom/rama.htm. Yes, there was a 'bodge' to convert one of the 1K EPROM sockets to...
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 12th, 2019, 07:12 AM
    daver2 replied to a thread Nascom in Other
    Thanks. So the first thing I would look for is the 4K block address decode logic implemented by the RAM A card. I haven't got access to the...
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 12th, 2019, 01:45 AM
    daver2 replied to a thread Nascom in Other
    So when you say the NASCOM is 'losing' much of its available RAM, what do you mean? If you have RAM up to $0FFF - then this is the on-board SRAM. I...
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 9th, 2019, 12:02 PM
    daver2 replied to a thread Nascom in Other
    If C17 is broken - I would replace it. It is in the cassette demodulator circuit. I don't think it has a major function to play - but just in case......
    223 replies | 15610 view(s)
  • daver2's Avatar
    March 9th, 2019, 11:52 AM
    daver2 replied to a thread DECtapes on Ebay. in DEC
    And that's exactly what the German to English translation says as well... Dave
    2 replies | 196 view(s)
  • daver2's Avatar
    March 8th, 2019, 01:40 PM
    daver2 replied to a thread Nascom bad again in Other
    IC2 should NOT be enabled if nothing is plugged into the external NASBUS. Either you have a faulty 81LS95 or something driving it is faulty. What...
    10 replies | 474 view(s)
  • daver2's Avatar
    March 8th, 2019, 07:14 AM
    daver2 replied to a thread PDP-11/10 with TU60 on Ebay. in DEC
    Just thinking the same myself - although shipping to the UK will be somewhat prohibitivly expensive! Dave
    7 replies | 332 view(s)
More Activity

1 Visitor Messages

  1. View Conversation
    http://www.vintage-computer.com/vcfo...ad.php?t=12058

    EPROM's don't last forever, and eventially you have to reburn them which I think is why your Tektronix isn't working. Have you tried contacting the guy to that website to see if he can reburn your EPROM's for you? Or if you have a EPROM burner, have you asked him to email you an image copy?
Showing Visitor Messages 1 to 1 of 1
About GanjaTron

Basic Information

About GanjaTron
Location:
Switzerland

Signature


"END OF LINE" [MCP, 1982]
"An admin that isn't a bit hackerish is just the guy mopping up the keyboard" [Phrack V0b I3f P12]
"Any appearance of danger is simply a device to enhance your experience" [Futureworld, 1976]

Statistics


Total Posts
Total Posts
150
Posts Per Day
0.03
Visitor Messages
Total Messages
1
Most Recent Message
October 26th, 2008 11:06 PM
General Information
Last Activity
September 12th, 2018 11:43 PM
Join Date
January 10th, 2007
Referrals
0
Home Page
http://www.ganjatron.net

2 Friends

  1. daver2 daver2 is offline

    Senior Member

    daver2
  2. Philcogrump Philcogrump is offline

    Member

    • Send a message via AIM to Philcogrump
    Philcogrump
Showing Friends 1 to 2 of 2