Am Freitag, 13. Oktober 2023, 13:30:16 CEST schrieb Frank Wolf: > Hi! > > As many here know the 6502 actually fetches and discards the next opcode > when executing > > single byte instruction before actually fetching the OP code again and > it also write back actual > > data before writing the real data to a specific memory address; the so > called "dummy reads". > > Is there any easy way to detect or predict a dummy read? Maybe when > looking at some internal signals > > (e.g. Visual6502) without reimplementing the full instruction decoder? I'd just make a table with 256 entries, and in each entry use the bits to indicate those dummy cycles. That makes "is this a dummy cycle" a simple lookup based on current instruction and current cycle. What are you trying to do? :) -- http://hitmen.eu http://ar.pokefinder.org http://vice-emu.sourceforge.net http://magicdisk.untergrund.net Adults are obsolete childrenReceived on 2023-10-13 14:00:23
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