What's the best way to pause a 68000 CPU? I'm diagnosing an old game PCB and want to pause the screen so I can concentrate on fixing a hard to track down graphics error.
Pausing it would help immensely.
No doubt I'll also have to disable any watchdog otherwise it will just reset.
Thanks
Drive the *HALT line to a logical 0.
Thanks - could I just Ground it? Or should I use a resistor?
You could try a 1K resistor without hurting anything. Do you have a schematic of the circuitry in question? What does the *HALT pin connect to?
No schems I'm afraid.
Guess I could just try it - will do later.
Thanks
Usually shorting TTL outputs to GND won't hurt anything. Since the HALT pin can also be an output from the 68K there's probably one or more open collector devices driving this pin. As long as it's not tied to +5, I doubt shorting to GND would hurt anything. To be even safer, you could try a 100 ohm resistor if the 1K doesn't work, then try shorting to GND if the pin is not tied to +5.
You're welcome.
Thanks, worked a treat. :-)
You're welcome. Did you use a resistor, or just short to GND?
Just for the record, a 68000 (along with just about every other single-chip microprocessor ever made), is not TTL.
Isaac
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