opcode guide with cycle count?

Petruza · Post by **Petruza** » Tue Mar 10, 2009 6:34 pm

I think I saw somewhere a 6502 opcode guide with how many cpu cycles each one spent, but I can't find it now.
Is there any? can you point it out? thanks!

qeed · Post by **qeed** » Tue Mar 10, 2009 6:51 pm

http://www.6502.org/users/andre/petinde ... /64doc.txt

frantik · Post by **frantik** » Tue Mar 10, 2009 7:50 pm

i like this one

http://nesdev.com/6502.txt

Petruza · Post by **Petruza** » Wed Mar 11, 2009 5:12 am

Thanks² !

Disch · Post by **Disch** » Wed Mar 11, 2009 7:43 am

Beware that 6502.txt has many critical typos (like the wrong opcode listed in places). This is why I don't like to recommend it to people as a reference doc, even though it does a good job of explaining things.

I'd recommend you use obelisk as a reference to double check against 6502.txt:

http://www.obelisk.demon.co.uk/6502/reference.html

I've been using it for a primary reference for years now and I can assure it is error-free.

Though if you want details about what the CPU is doing on each cycle -- it doesn't get better than this doc (scroll down to near the end):

http://nesdev.com/6502_cpu.txt

That's only really useful for emulator devs, though.

frantik · Post by **frantik** » Thu Mar 12, 2009 7:54 am

i like 6502.txt for the way it i laid out.. didn't know about the errors though

actually seeing the description of each clock cycle is cool though, makes it easier to remember how many cycles each operation takes

Petruza · Post by **Petruza** » Thu Mar 12, 2009 10:42 am

Thanks disch! they are great.

CartCollector · Post by **CartCollector** » Sat Mar 21, 2009 8:33 pm

http://www.6502.org/tutorials/6502opcodes.html

Easy to use, and even includes info on what each instruction does.

frantik · Post by **frantik** » Sat Mar 21, 2009 8:51 pm

^ yeah i found that one recently and i have to say it's quite nice