On Tue, 10 Jun 2014, Gerrit Heitsch wrote: > The only way I can see to start that program is to feed the necessary > JMP instruction and then return RESET to +5V at the right moment after > supplying the last byte. The catch is the meaning of 'the right > moment'. What if the test program would do this by itself? After all, the 6500/1 would be running in a dedicated test circuitry which resets the thing, then goes to +10V and taps in the test program (probably as a series of LDA / STA sequences). Then comes the final jump to address $0000 where the first commands are setting an output port pin so that reset falls down to +5V and now the ROM can e.g. be dumped via the serial output. That way, the external circuitry only needs to take care of invoking the test configuration and tapping in the program. While I don't have a 6500/1 at hand, I do have a fair share of 6500/11 for experimenting, assuming that these use a similar test setup. Rainer Message was sent through the cbm-hackers mailing listReceived on 2014-06-10 19:03:40
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