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Thread: Reset switch for PET 8032

  1. #1
    Join Date
    Apr 2011
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    Default Reset switch for PET 8032

    Hi all,
    I wanted to make a simple reset switch for my 8032, to spare wear and tear on the machine while I mess around with some software development.
    I know the J4 header has /RST on pin 22. Is it safe to just switch this pin to GND through a pushbutton? Or might there be a better/safer way to reset the 8032 externally?
    Thanks!

  2. #2
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    Yes that is OK - the switch is pulling down current through a 1kOhm resistor R15. The 7417 buffer (UD15 output pin 6) is open collector.

    Use a 100 Ohm resistor to GND if you prefer.

    If you are resetting the PET to do software development though (recover from a crash) - you may need to consider another avenue as the DRAM refresh may be interrupted during a reset? Just a thought...

    Dave

  3. #3

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    Quote Originally Posted by daver2 View Post
    Yes that is OK - the switch is pulling down current through a 1kOhm resistor R15. The 7417 buffer (UD15 output pin 6) is open collector.

    Use a 100 Ohm resistor to GND if you prefer.

    If you are resetting the PET to do software development though (recover from a crash) - you may need to consider another avenue as the DRAM refresh may be interrupted during a reset? Just a thought...

    Dave
    Nope, refresh only depends on two counters that are fed from the master clock generator. That's not affected by a CPU reset.
    Frank

  4. #4
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    Note that if you hold the DIAGNOSTIC line low while resetting you will enter the monitor instead of doing a full reset. See:
    http://www.6502.org/users/andre/petindex/repairs.html

    There's also this thread:
    http://www.vcfed.org/forum/showthrea...set-Switch-Mod
    Last edited by MikeS; September 4th, 2019 at 10:20 AM.

  5. #5
    Join Date
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    Quote Originally Posted by gubbish View Post
    I know the J4 header has /RST on pin 22. Is it safe to just switch this pin to GND through a pushbutton? Or might there be a better/safer way to reset the 8032 externally?
    Grounding pin 22 leads to a hard reset with all user memory cleared to $AA. Mike's links have a soft reset where user memory is not cleared for examination in the M/L Monitor. From the monitor (in BASIC 4) a Go command to FD16 ( .g fd16 ) will perform a hard reset.

    The pin opposite pin 22 on the connector is ground as are all the pins in that row.

  6. #6
    Join Date
    Apr 2011
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    Thanks very much, this is quite useful. I rigged up the hard reset switch to ground pin 22 through a 100 ohm resistor, which works well. May include the option to go to the monitor as well.

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