From: silverdr; on Thursday, May 23, 2013; at 11:52 AM -0400 > > On 2013-05-23, at 16:17, Greg King wrote: > >>> 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). > > That was actually the question from my original post: what does the > "test bit", AKA "test mode", do to the machine? > >> But, the new test bit doesn't do that -- and, the change is momentary. > > What do you mean? If bit 2 can't hold the "cleared" state, then, with > ror $d030, the "set" state will be shifted to bit 1. Meaning: no matter what > was the state of bit 1 before the action -- after the test, this bit will be set, > right? Darn! I didn't see that. Segher and you are right. So, my "great" solution isn't as great as I thought it is. :-/ A little "bloat" could fix it: _is_c64: lda $d030 asl $d030 ror $d030 sta $d030 lda #0 rol a rts But, I have another idea: _is_c128: inc $d030 lda $d030 dec $d030 eor $d030 rts Does that one pass peer review? :-) Message was sent through the cbm-hackers mailing listReceived on 2013-05-24 19:00:08
Archive generated by hypermail 2.2.0.