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  1. Well done that man :-)! Have you tested all of...

    Well done that man :-)!

    Have you tested all of the PET functions yet?

    Do you have a cassette to load space invaders for example!!!

    We have had people get this far - and then something else...
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    I fired up my AIM-65 emulator this afternoon and...

    I fired up my AIM-65 emulator this afternoon and I found that it already contained the AIM 65 DOS VERSION 1.0 ROM image.

    I remember now what the problem was - I couldn't make sense of the ROM...
  3. Thread: Microkit 8/16

    by daver2
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    5,830

    I was merging the screen display from the other...

    I was merging the screen display from the other 'half' of the EPROM - but I am not making much sense of it...

    Can you just confirm the wiring of the adapter board that you made up please?

    There...
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    I am guessing (from looking at the photograph)...

    I am guessing (from looking at the photograph) that there are two parts to this.

    1. Is an adapter from the expansion bus to a ‘commercial’ bus.
    2. A video card for the ‘commercial’ bus.

    I...
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    Nice purchase! Dave

    Nice purchase!

    Dave
  6. Thread: Microkit 8/16

    by daver2
    Replies
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    5,830

    I can't answer that question though. Is there...

    I can't answer that question though.

    Is there a -9V generator on the board?

    Presumably you can follow the -9V pin(s) from the EPROM to where it is sourced from - and see where it takes you...
    ...
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    Excellent work Tom. Dave

    Excellent work Tom.

    Dave
  8. This information is from soooo long ago! Use...

    This information is from soooo long ago!

    Use the Windows Installation disk.

    Answer the language and time questions.

    Click Next.

    Select Repair your Computer.
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    At 1V/div those traces are even more suspect... ...

    At 1V/div those traces are even more suspect...

    We need to ‘poke around’ the databus buffers first...

    Dave
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    I thought I would be a bit controversial for a...

    I thought I would be a bit controversial for a change...

    Going from a Z80 to an 8080 (or 8085) would be a nightmare, the other way is relatively painless.

    I had to disassemble some 8085 code...
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    There is something not ringing true here... We...

    There is something not ringing true here...

    We know for a fact that the 8080 variant of Altair BASIC does not run on a Z80. There are some slight flag differences between the operation of the two...
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    Even at 5V/div and no timebase information - they...

    Even at 5V/div and no timebase information - they do look suspect to me on first glance...

    I would suggest having a look at pins 1 and 19 of the RAM data bus buffers I10 and I11.

    These pins...
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    Zilog would have had test systems and a...

    Zilog would have had test systems and a development system of some kind.

    Reference is even made to a development system for the Z80 in the recorded interview at CHM...
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    Yep, I did process that. I just wanted to add a...

    Yep, I did process that. I just wanted to add a warning about not connecting a LS TTL logic signal directly to +5V.

    You could replace the pull-up resistor on /INIT with a slightly higher-value one...
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    Most things have a logical cause when you get...

    Most things have a logical cause when you get into them!

    4.75V on /INIT is fine. I wouldn’t bother with anything else. Just a warning, don’t wire a logical signal directly to +5V without a pull-up...
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    A 'modern' 1702 programmer (is there such I thing...

    A 'modern' 1702 programmer (is there such I thing I ask myself) would probably be serial or centronics parallel - hence the 25 way plug or socket.

    I would guess this thing as address, data and...
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    >>> Correct, I think he should know this, as he...

    >>> Correct, I think he should know this, as he used another PET "PSU" to power-on the board.

    There is a little more to the interconnection of the capacitor than that though (if I remember...
  18. Thread: Genrad 2115

    by daver2
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    158

    As this is your first post - welcome to VCFED. ...

    As this is your first post - welcome to VCFED.

    Don't forget to put your location into your profile. You never know, there may be some more VCFED people in your area...

    Document your system...
  19. I would like to bet that all he has done is to...

    I would like to bet that all he has done is to probe around on the motherboard with his multimeter.

    The PDF file is the data sheet for the device in question. These devices are still mass...
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    Thanks, I was looking at the schematic for the...

    Thanks, I was looking at the schematic for the X-Y driver...

    One possibility to think about would be an ac signal generator coupled to the faulty line by a low-valued capacitor. This should...
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    Don’t forget that the large smoothing capacitor...

    Don’t forget that the large smoothing capacitor is also external to the PET mainboard.

    Dave
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    Looking at the schematics for the H212 (MM8-EJ) I...

    Looking at the schematics for the H212 (MM8-EJ) I see that EMA2 appears on drawing sheet 3 and is coupled to E14 pin 9 via wire link W1.

    EMA2 should select between the upper and lower 4K banks.
    ...
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    >>> I haven't had a chance to try any of the...

    >>> I haven't had a chance to try any of the suggestions, but just wanted to resolve your confusion due to my less-than well-organized post above. The /CS trace above wasn't taken with the NOP...
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    Good catch Dave. Dave

    Good catch Dave.

    Dave
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    I am getting a little confused now... With the...

    I am getting a little confused now...

    With the NOP generator in place, you should see each ROM /CS pin being selected (in turn) for 1/16th of the time.

    This should be the first step if you are...
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