>> _c64_check: >> asl $d030 >> ror $d030 >> adc #0 <-- can't work >> rts > > GIGO (Garbage In, Garbage Out) > > We can't know what would be already in the accumulator; therefore, > we must set it to a known value. Ugh, yes. >> Or, if you return in the carry flag instead of in .A: [This is not what I wrote; please don't edit quotes]. >> >> _c64_check: >> asl $d030 >> ror $d030 >> rts > > I was thinking of a C-callable library function: Is there a standard C ABI for 6502? I have never seen one, do you have a link perhaps? >> Unfortunately, I don't think any of these work; they all set >> the test-mode bit (bit 1) to 1 (on)? > > Does that matter? The original test bit (in $d016) crashed the > system because it disabled the dynamic RAM refresh (therefore, it > was removed). But, the new test bit doesn't do that -- and, the > change is momentary. Are you saying the bit auto-clears? Docs on the web disagree (but of course those could be wrong). Segher Message was sent through the cbm-hackers mailing listReceived on 2013-05-23 21:00:08
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