www.mycpu.eu (C) 2023 by Dennis Kuschel 

In some configurations, dependend on used parts or the length of the backplane bus, the MyCPU seems to be very instable and crashes often. This page collects all known fixes that may increase your system's stability.

If you observe stability problems of your MyCPU please check this list:
  • MyCPU Microcode Control Board
    • Try different positions for Jumper JP4
    • Use 74HCxxx types for ICs 6, 7, 12, 13, 14 and 15
    • Use faster EPROMs
  • MyCPU Signal Decoder Board
    • Use a 74HC138 for IC20, -or-
    • insert 47 Ohm resistors in the signals at IC20 pin 11 and pin 12 (use SMD type resistors on board top layer)
  • Backplane Bus
    • Place the CPU at the very left or very right end on the backplane
    • Place the Power Supply at the other end (it includes termination resistors)
    • Try different positions for the other boards on the bus

A common method to reduce stability issues is:  Don't use 74ACxxx -parts at all!
The second method is to reduce oscillator frequency to 16MHz or lower.

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