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  • daver2's Avatar
    Today, 12:16 PM
    daver2 replied to a thread Epson Fx86e in CP/M and MP/M
    Well it beats shovelling snow! What was your problem in the end with the printer? Dave
    22 replies | 294 view(s)
  • daver2's Avatar
    Today, 09:31 AM
    Thanks Don. I was using an old version of this (pre Rhialto modifications). However, the TRAP instruction appears to generate an error. There...
    16 replies | 348 view(s)
  • daver2's Avatar
    Yesterday, 01:45 PM
    I am not sure those disk images have the source code to the PDP P-code emulator though (although I haven't looked yet - so I may be speaking...
    16 replies | 348 view(s)
  • daver2's Avatar
    Yesterday, 10:31 AM
    daver2 replied to a thread PET 2001 Keyboard Issue in Commodore
    >>> Updates to follow soon. We wait with interest... Dave
    8 replies | 77 view(s)
  • daver2's Avatar
    Yesterday, 06:27 AM
    We had a problem at work with some SRAM on a card that we are remanufacturing from the 80s. Our first problem was power supply related. The...
    229 replies | 16004 view(s)
  • daver2's Avatar
    Yesterday, 06:09 AM
    daver2 replied to a thread PET 2001 Keyboard Issue in Commodore
    First of all, welcome to VCFED. We have found that some PIAs work and others don’t. Not sure which are which though. dave_m may be keeping track...
    8 replies | 77 view(s)
  • daver2's Avatar
    March 4th, 2021, 09:53 AM
    daver2 replied to a thread Epson Fx86e in CP/M and MP/M
    I would wait for BUSY=0 and /ACK=1 (as you are doing at the moment). Next, send the desired data byte out and wait for 0.5 us (data setup time). ...
    22 replies | 294 view(s)
  • daver2's Avatar
    March 4th, 2021, 09:41 AM
    Thanks Al. I will have a look. Hopefully, that will save some time and hassle! Dave
    16 replies | 348 view(s)
  • daver2's Avatar
    March 4th, 2021, 06:12 AM
    >>> Also I played with UCSD Pascal on an Apple II recently. Cool stuff! >>> I learned LSI11 was the devleopment machine for it. >>> Any pointers to...
    16 replies | 348 view(s)
  • daver2's Avatar
    March 4th, 2021, 03:05 AM
    daver2 replied to a thread Epson Fx86e in CP/M and MP/M
    The manual states CR, but you will still need to output a LF yourself (unless you have the appropriate DIP switch set). Check the words in Appendix A...
    22 replies | 294 view(s)
  • daver2's Avatar
    March 2nd, 2021, 11:04 AM
    That’s one of the references I was trying to find. I suspect the voltage will fall not rise if the capacitor fails open circuit though. Dave
    229 replies | 16004 view(s)
  • daver2's Avatar
    March 2nd, 2021, 07:05 AM
    Tom, My guess about the isolated transformer secondary and capacitor would be a harmonic filter of some description. If the capacitor goes...
    229 replies | 16004 view(s)
  • daver2's Avatar
    February 28th, 2021, 02:19 PM
    No, I haven’t tried this procedure before. I am just thinking out of the box :-)! It is good that you are seeing some coupling though. I do...
    75 replies | 4920 view(s)
  • daver2's Avatar
    February 28th, 2021, 02:34 AM
    Yes, address $0000 looks fine. However, the interesting thing would be address $0001 (as stated back in post #164). The fact that the machine...
    177 replies | 6883 view(s)
  • daver2's Avatar
    February 25th, 2021, 07:56 AM
    daver2 replied to a thread Cbm 8050 dual drive in Commodore
    Hello again Ilpaninaro. When you say "works fine" do you mean it powers up and the green light comes on only? This is an indication that the...
    3 replies | 117 view(s)
  • daver2's Avatar
    February 24th, 2021, 02:01 AM
    daver2 replied to a thread Hi, I am Dalmas. in Introductions
    I have been able to find the schematics for the SIM4-01 and -02 but not the -03. If they don't exist online, could I ask that you preserve them...
    11 replies | 262 view(s)
  • daver2's Avatar
    February 24th, 2021, 12:22 AM
    Welcome. We are a global mix of both hardware and software. Plenty of people here that would welcome a new member! I am a member of a...
    3 replies | 133 view(s)
  • daver2's Avatar
    February 24th, 2021, 12:12 AM
    daver2 replied to a thread Hi, I am Dalmas. in Introductions
    Welcome to VCFED... Nice little card you have there. Let me get back to you presently about how much of a SIM4-03 you can test without a...
    11 replies | 262 view(s)
  • daver2's Avatar
    February 23rd, 2021, 11:09 AM
    daver2 replied to a thread PET 2001 Cover? in Commodore
    There may be a small market for these types of covers of course... Dave
    3 replies | 108 view(s)
  • daver2's Avatar
    February 21st, 2021, 08:07 AM
    daver2 replied to a thread Tek 405x web-browser emulator in Other
    Thanks Jos, I will add some of my microcode logic diagnostic code to the specific addresses around where it is playing with these locations to see...
    264 replies | 31661 view(s)
  • daver2's Avatar
    February 21st, 2021, 07:07 AM
    daver2 replied to a thread Tek 405x web-browser emulator in Other
    I think (:-)) I have put all of the infrastructure back in for interrupts now... I had to remove all of my diagnostic code within the I/O reads...
    264 replies | 31661 view(s)
  • daver2's Avatar
    February 21st, 2021, 06:26 AM
    daver2 replied to a thread Tek 405x web-browser emulator in Other
    It looks like the write to ROM from the microcode is intentional (unless I have misunderstood the I/D logic somewhere - which wouldn't surprise me of...
    264 replies | 31661 view(s)
  • daver2's Avatar
    February 21st, 2021, 03:54 AM
    The timing should be locked to a clock pulse (one of the 8 phases) and not left to the whim of a gate delay or pull-down capability. At that...
    177 replies | 6883 view(s)
  • daver2's Avatar
    February 21st, 2021, 02:27 AM
    daver2 replied to a thread Tek 405x web-browser emulator in Other
    Hi Monty, Yep, I have that document. This is a listing of the microcode not the firmware itself. It passes the 4052/4054 determination OK...
    264 replies | 31661 view(s)
  • daver2's Avatar
    February 21st, 2021, 01:26 AM
    >>> I know Dave doesn't like swapping stuff randomly, but It worked, so I would take it! Good to see that it passes my PETTESTER code (that...
    177 replies | 6883 view(s)
  • daver2's Avatar
    February 20th, 2021, 04:24 PM
    daver2 replied to a thread Tek 405x web-browser emulator in Other
    Hi Monty, Yes and no... I keep having a go. I get a bit further and then hit a problem and get distracted by real paying work! I then go...
    264 replies | 31661 view(s)
  • daver2's Avatar
    February 20th, 2021, 05:57 AM
    yep, classic short circuit tantalum capacitor across the power rails by the looks of it. Once it has gone short circuit, it takes the voltage down...
    15 replies | 440 view(s)
  • daver2's Avatar
    February 19th, 2021, 01:20 PM
    Chuck, That’s a nice description and avoids the ‘lazy write’ issue. Dave
    46 replies | 816 view(s)
  • daver2's Avatar
    February 19th, 2021, 11:04 AM
    daver2 replied to a thread PDP11 GUI Crash in DEC
    I am guessing that a new build of PDP11 GUI is going to be required. Either because Microsoft have 'retired' a function or that the parameters have...
    6 replies | 330 view(s)
  • daver2's Avatar
    February 19th, 2021, 02:31 AM
    You need about 10 posts... From the trace back in post #123 I think we concluded that address $0000 was OK and things started to fail at address...
    177 replies | 6883 view(s)
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SW/HW design engineer

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