Am Sonntag, 15. Oktober 2023, 21:03:01 CEST schrieb laughton_at_cyg.net: > > Perhaps using one of the 6502 variants that indicate "next instruction" > > on a pin is an option? > > groepaz, I'm only aware of one such variant, and that is the 65C816. Is > that what you had in mind? > > The '816 does wake up in 6502 "Emulation Mode," so perhaps it's suitable > for Frank's needs. And as you probably know, it has two outputs (VPA > and VPD) which, when both low, reveal that a dummy cycle is in progress. > VPA and VPD get updated early in the cycle, same as the address lines. > So, it's an early indication... but not quite a *prediction*. > > Hope this helps, I was thinking of the SYNC signal that some 6502 or 65C02 chips expose on a pin, this could be used to detect an opcode fetch, and to reset a counter that counts the cycles into the instruction (which then allows to determine if its a dummy cycle or not in a lookup table) -- http://hitmen.eu http://ar.pokefinder.org http://vice-emu.sourceforge.net http://magicdisk.untergrund.net Ein Zyniker ist ein Schuft, dessen mangelhafte Wahrnehmung Dinge sieht wie sie sind, statt wie sie sein sollten. <Ambrose Bierce>Received on 2023-10-16 00:00:07
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