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  • daver2's Avatar
    Yesterday, 12:42 PM
    daver2 replied to a thread PDP8E & Fortran IV in DEC
    A little wiser now... I wrote my own simple program called TESTDI.FT (it should have been TESTDIV.FT but I forgot about the 6 character...
    23 replies | 714 view(s)
  • daver2's Avatar
    Yesterday, 09:57 AM
    daver2 replied to a thread PDP8E & Fortran IV in DEC
    After looking through the FORTRAN runtime code I see that the "DIVIDE BY 0" error message is output if no other match is found by the error routine!...
    23 replies | 714 view(s)
  • daver2's Avatar
    Yesterday, 07:51 AM
    daver2 replied to a thread PDP8E & Fortran IV in DEC
    I have just found the assembler source code for the FORTRAN run-time system at...
    23 replies | 714 view(s)
  • daver2's Avatar
    Yesterday, 06:36 AM
    daver2 replied to a thread PDP8E & Fortran IV in DEC
    That might explain your MAINDECs - the CPU may be OK, but the EAE not... Yep. Compile and get your program working 100% reliably on SIMH and then...
    23 replies | 714 view(s)
  • daver2's Avatar
    Yesterday, 04:21 AM
    daver2 replied to a thread PDP8E & Fortran IV in DEC
    Thanks for the update - I am a bit more 'clued up' now... Just because your FORTRAN program doesn't use division - doesn't mean that 'under the...
    23 replies | 714 view(s)
  • daver2's Avatar
    June 27th, 2017, 01:04 PM
    daver2 replied to a thread PDP8E & Fortran IV in DEC
    Can you remind me, what 'disk' drive are you running your PDP-8 from? If one of your FORTRAN files became corrupt (the rogue version number) what...
    23 replies | 714 view(s)
  • daver2's Avatar
    June 24th, 2017, 11:21 AM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    Well done :-)! Dave
    140 replies | 6437 view(s)
  • daver2's Avatar
    June 23rd, 2017, 11:46 PM
    daver2 replied to a thread PDP8E & Fortran IV in DEC
    Mike, Usually things like this can be caused by a faulty CPU or memory. This is the problem with a hobby like this - the equipment you have may...
    23 replies | 714 view(s)
  • daver2's Avatar
    June 22nd, 2017, 09:35 AM
    daver2 replied to a thread Saving ROM data from Tek 4052 in Other
    I used to work with Philip many moons ago, so it may be an opportune time for me to contact him and start a dialogue... I will also copy my...
    52 replies | 3681 view(s)
  • daver2's Avatar
    June 19th, 2017, 11:25 PM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    Interesting. No time to dig further (business trip in a few minutes) but I note that the MK4118 makes use of Pin 19 as /L (Latch) whereas the...
    140 replies | 6437 view(s)
  • daver2's Avatar
    June 19th, 2017, 01:05 PM
    daver2 replied to a thread Saving ROM data from Tek 4052 in Other
    So, I got home and found that I had downloaded all of your documentation from a PM that you had sent me ages ago... Dooooo!!! Anyway, I know a lot...
    52 replies | 3681 view(s)
  • daver2's Avatar
    June 19th, 2017, 04:08 AM
    daver2 replied to a thread Saving ROM data from Tek 4052 in Other
    Thanks. I will pick them up tonight - work won't let us look at file sharing services... I have a business trip Tue/Wed - so I will need something...
    52 replies | 3681 view(s)
  • daver2's Avatar
    June 18th, 2017, 01:51 PM
    daver2 replied to a thread Saving ROM data from Tek 4052 in Other
    I got your PM. Sorry, a bit too busy at the moment with work... Question. Are the technical manuals online somewhere detailing the hardware and...
    52 replies | 3681 view(s)
  • daver2's Avatar
    June 18th, 2017, 02:58 AM
    My guess (although it is strange to see the headers missing) is that it formed part of an embedded solution - possibly connected to HPIB/GPIB...
    5 replies | 352 view(s)
  • daver2's Avatar
    June 16th, 2017, 10:56 AM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    Getting further! I seem to remember I had mine configured as follows: 2 blocks of 4K memory = LSW1/7=OPEN and LSW1/8=OPEN. /BLOCK A wired to...
    140 replies | 6437 view(s)
  • daver2's Avatar
    June 12th, 2017, 05:28 AM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    Back in the early days the NASCOM 2 was supposed to ship with on-board RAM from 0x1000 upwards in addition to the workspace from 0x0C00 to 0x0FFF....
    140 replies | 6437 view(s)
  • daver2's Avatar
    June 10th, 2017, 11:03 PM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    Agreed, this would be very useful data to have. Dave
    140 replies | 6437 view(s)
  • daver2's Avatar
    June 8th, 2017, 10:16 AM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    I have attached my timing diagram (twice - oops!) to post #109. You can even read it whilst lying in bed... This was one of the 'fixes' for...
    140 replies | 6437 view(s)
  • daver2's Avatar
    June 8th, 2017, 06:45 AM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    I can post some words as to how I think the video circuitry works here - but you will have to wait until I get home to upload a waveform diagram. I...
    140 replies | 6437 view(s)
  • daver2's Avatar
    June 8th, 2017, 02:43 AM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    Sorry, I forgot yesterday my services were required at a concert (moving all of our A/V gear out of the Church so a professional company could move...
    140 replies | 6437 view(s)
  • daver2's Avatar
    June 6th, 2017, 05:38 AM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    Sorry guys - real work has got in the way. I will respond tomorrow morning (Wednesday) - I have the day off. Dave
    140 replies | 6437 view(s)
  • daver2's Avatar
    June 4th, 2017, 12:04 PM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    Nice to know that unbuilt NASCOM 2 went to a good home! My friend came good today with a lot of information that I will pass on tomorrow if that...
    140 replies | 6437 view(s)
  • daver2's Avatar
    June 2nd, 2017, 02:20 PM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    Hi Harry, Yes, that is interesting... Pin 1 of IC65 is the same piece of wire as pin 11 of IC67 (our problem clock)... Hmmm, perhaps this...
    140 replies | 6437 view(s)
  • daver2's Avatar
    June 2nd, 2017, 11:18 AM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    A typo. may have crept in on post #85... 74LS20 not 74LS30 (just want to make sure you don't order the wrong thing)... I have sent an e-mail to...
    140 replies | 6437 view(s)
  • daver2's Avatar
    June 2nd, 2017, 07:11 AM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    That's a bl**dy good spot there that man! Interestingly, both the schematics and the hardware manual (it contains a parts list) on the...
    140 replies | 6437 view(s)
  • daver2's Avatar
    May 30th, 2017, 11:22 PM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    It wouldn't surprise me what you are seeing - I was expecting this modification to introduce some 'strangeties' into the display. The interesting...
    140 replies | 6437 view(s)
  • daver2's Avatar
    May 30th, 2017, 12:53 PM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    The next test would be to bend pin 11 of IC67 out and temporarily connect it to pin 13 of IC49. Again - I don't expect anything to change, but if...
    140 replies | 6437 view(s)
  • daver2's Avatar
    May 30th, 2017, 04:30 AM
    daver2 replied to a thread Nascom 2.Troubleshooting in Other
    The SN suffix is Texas Instruments. I wasn't really expecting any change in the display by the modification to IC65 pin 1. At least your test...
    140 replies | 6437 view(s)
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SW/HW design engineer

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