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  1. Replies
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    It's a bit blurred, but it does look like 0ee2...

    It's a bit blurred, but it does look like 0ee2 (which is bank 0).

    Can I ask exactly what devices you have used in bank 0? Are they all from the same manufacturer with the same part number? Can you...
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    If you look at the second image back in post...

    If you look at the second image back in post #387, the address is 4b33 in that case (the only 16-bit hex number displayed). Addresses 0000 through 3fff are in bank 0 whilst addresses 4000 through...
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    >>> I inserted Cia and Via for keyboard values=...

    >>> I inserted Cia and Via for keyboard values= 00

    Ah, so the chips were out for the keyboard. When the 'countdown' screen is displayed (with the ROM checksums displayed) pressing a key should...
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    I came back this morning. Over on 2 on Wed and...

    I came back this morning. Over on 2 on Wed and then at a contractor's on Thu.

    We must go out for a curry next time I am up. The regular haunt is the Bombay Balti.

    Dave
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    The memory test takes forever (!) it tests all of...

    The memory test takes forever (!) it tests all of memory all of the time in a loop. You should get an incrementing PASS counter every time it successfully completes one entire memory pass.

    I see...
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    Ok, So, the ROM checksums are good for BASIC 2...

    Ok,

    So, the ROM checksums are good for BASIC 2 (7800 3838 506a 7c98).

    If you didn't have a keyboard connected, then the keyboard PIA must be duff (or something else is causing the '17'...
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    Just got back from my business trip from the cold...

    Just got back from my business trip from the cold and dark North West of England.

    I see you are starting to get some success now (and I missed all of the action)!

    I will check the EPROM...
  8. I just edited my post with a bit of further...

    I just edited my post with a bit of further information - but a good clean never did anyone any harm either :-)!

    Dave
  9. It looks like two additional signals on top of...

    It looks like two additional signals on top of the VIDEO ON pulse.

    CB1 should be an input. It appears to be (erroneously) shown as an output on the Commodore schematics?

    Therefore, with UC7 IN...
  10. Might be worth having a look at the VIDEO ON...

    Might be worth having a look at the VIDEO ON signal at UC7 pin 18 with both UC7 installed and not.

    Dave
  11. Yep. There are only three (3) devices: Sheet...

    Yep. There are only three (3) devices:

    Sheet 2:

    UC6 (6520)

    Sheet 3:

    UC5 (6522)
    UC7 (6520)
  12. +1. UC7 is the beastie... Dave

    +1.

    UC7 is the beastie...

    Dave
  13. Look at the CPU /IRQ line with an oscilloscope...

    Look at the CPU /IRQ line with an oscilloscope whilst the cursor goes mad. Does the /IRQ line go mad at the same time?

    I suspect the problem is the keyboard PIA/VIA or whatever device it is. Not...
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    Yup. I suspect the RAS signal we are seeing is...

    Yup.

    I suspect the RAS signal we are seeing is the refresh but there is no RAS for the memory access. That's as I understand the two halves of the 7474 work at any rate.

    And one of the duff...
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    Yep, The last two bits of the 164 shift...

    Yep,

    The last two bits of the 164 shift register appear to be stuck at '0' and '1' respectively.

    Having changed the inverter in the output of 164 QG, things didn't improve, hence it is not...
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    That's what I said. I think the 164 is kaput -...

    That's what I said. I think the 164 is kaput - hence swapping any other device other than the 164 won't cure your problem (although I think there is a small probability that the 74S04 may have been...
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    You can turn it on. Remove the NOP generator...

    You can turn it on.

    Remove the NOP generator and see what my PETTEST does...

    Don't be surprised if it fails in the same way though...

    Since we may have fixed one problem (the potentially...
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    I like those signals better - as UH2 pins 13 and...

    I like those signals better - as UH2 pins 13 and 12 are now acting as a 'proper' inverter!

    I think you ought to get a replacement 74164 to replace UH3 next.

    Dave
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    Hi, Just got back from my walk - after...

    Hi,

    Just got back from my walk - after watching the Japanese F1 GP.

    I did suggest waiting for Dwight and Dave_m but...

    Yes, measure the points identified in post #354 again.

    Fingers...
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    I would guess the 74F04 should be an OK...

    I would guess the 74F04 should be an OK replacement. Just put it in a socket though...

    Perhaps wait though until Dwight and Dave_m 'wake up' to double-check the results first?

    Dave
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    A quick thought before swapping chips... Can...

    A quick thought before swapping chips...

    Can you just check the PCB tracks around UH2 and UH3 checking for any obvious short or open circuits.

    Dave
  22. Hi, I keep forgetting how good the Tektronix...

    Hi,

    I keep forgetting how good the Tektronix terminals actually were. You keep posting image files that are extremely good for the time period.

    We had a PET and a Tektronix 4051 in our...
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    You are getting consistent results. The...

    You are getting consistent results.

    The problem could be either UH2 (74S04) or UH3 (74164).

    I deliberately chose pins that were either end of a couple of copper tracks - and the results from...
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    A few minutes spare before lunch... I suspect...

    A few minutes spare before lunch...

    I suspect that your reading for UH3/8 is OK. This signal should be 16 MHz. I suspect this is well in excess of the frequency that your logic probe will probably...
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    Nice job Peter. I especially like the thorough...

    Nice job Peter.

    I especially like the thorough commenting in the WinCUPL source files - an excellent example for everyone reading them!

    Question, is anyone going to make kits of parts - or even...
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