Subject: [stella] 6502 question (was INV+ ... ) From: "Erik Mooney" <erik@xxxxxxxxxx> Date: Tue, 6 Apr 2004 15:53:19 -0500 |
cybergoth@xxxxxxxx wrote: > Details! > > Greetings, > Manuel Patience! :) But it would help if anyone knows this. Does anyone have a 6502 reference as to exactly what JSR does on a cycle-by-cycle basis? I'm asking because I'm trying to do something crazy: hit RESP0 and RESP1 with fewer than 3 cycles difference. The only 6502 instruction that can (maybe) do two zeropage writes that fast is JSR. If the stack pointer is set to RESP1, then JSR would write to RESP1 and then RESP0 very quickly (the values written would be the current PC, but that's irrelevant.) ldx #RESP1 txs JSR nextinstruction nextinstruction Is that possible? How close together will P0 and P1 end up? ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
Current Thread |
---|
|
<- Previous | Index | Next -> |
---|---|---|
Re: [stella] Master Mind deluxe - k, Erik Mooney | Thread | Re: [stella] 6502 question (was INV, Eric Ball |
RE: [stella] Master Mind deluxe - k, Erik Mooney | Date | RE: [stella] 6502 question (was INV, Erik Mooney |
Month |