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Recent content by daver2

  1. daver2

    Cromemco dazzler replica project

    The random data it should look like is what you posted from step 28. It should 'swing' from 0V to 5V. What you are showing me in your second post above is a logic HIGH with a tiny bit of noise on it. I am guessing the pin goes HIGH when IC46 pin 15 goes LOW (i.e. the outputs of IC46 are...
  2. daver2

    Cromemco dazzler replica project

    So the 8 bits of 'random' data should go into IC46. Pin 1 of IC46 selects which 4 of the 8 bits is multiplexed to the output of IC46. Pin 15 of IC46 (when LOW) should enable the outputs of IC46. If we have a clock on IC46 Pin 1 (which we did) and a LOW signal on IC46 Pin 15 (which we did)...
  3. daver2

    Cromemco dazzler replica project

    It shouldn't matter at this stage whether they are 157 or LS157. Can you check the 8 input pins to IC46 and see if you are getting the same random data as on the previous steps. Dave
  4. daver2

    Cromemco dazzler replica project

    It doesn't matter. If you are seeing random signals coming in on the earlier step, they should be here... I am busy fir the next couple of hours though... Dave
  5. daver2

    Cromemco dazzler replica project

    Those pins are OK. Can you now check that you have a good connection between 0V and +5V for IC46 pins 8 and 16 respectively. If so, can you replace IC46 - it is probably toast. This may account for the completely white screen. Dave
  6. daver2

    Cromemco dazzler replica project

    Can you check IC46 pins 1 and 15 please. Dave
  7. daver2

    Cromemco dazzler replica project

    28 and 29 look OK. As you say, 30 not. I'll take a look after I have been fed! Dave
  8. daver2

    CBM 3040 Repair

    There are 6530 adapters of course if it turns out that one of these is duff. Dave
  9. daver2

    PDP11 - LSI11/02 and RQDX3

    I use minicom on a Pi. Set the intercharacter and interline delays for maximum speed and minimum boredom! Dave
  10. daver2

    Who bought my VT-100 and is missing a key?

    Put the key up for sale. You may get more money for it than the VT-100... Dave
  11. daver2

    CBM 3040 Repair

    Don't forget that there may be some ROM code in the special function devices? Dave
  12. daver2

    CBM PET 710 WITH BASIC PROBLEMS

    Use one probe of the oscilloscope, with the trigger set for that probe and adjust the timebase from slow to fast until something sensible appears - that is swinging from 0V to +5V. See if you can use the trigger level to get a stable display. If A7 is not oscillating, try A6, or A5... Dave
  13. daver2

    CBM PET 710 WITH BASIC PROBLEMS

    There is no point unless we know that the address bus is working. How do we know what device is writing to the data bus (if anything is)? We have no idea whether it is our EPROM or not... Dave
  14. daver2

    PDP11 - LSI11/02 and RQDX3

    According to this manual (which I can read better) http://www.bitsavers.org/pdf/dec/qbus/EK-RQDX3_RQDX3_Controller_Module_Users_Guide_Nov85.pdf the RD50 is not supported by the RQDX3. Of course, this may be because it was so old at the time that DEC thought that no one in their right mind would...
  15. daver2

    PDP11 - LSI11/02 and RQDX3

    You might want to start here: https://forum.vcfed.org/index.php?threads/looking-for-rqdx3-programming-examples.1210509/post-1210798. Post #7 with some links to some source code. I can't look at it myself at work though - github is blocked. Dave
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