ncoplin_at_orbeng.com
Date: 2002-10-31 08:40:37
Hi Cameron,
>> I was just catching up with old postings and this idea caught my
attention.
>> C't Aug1985 (German magazine) had an article about simulation of a 65C02
>> with a software 6502 emulator, and so it raises the question how about a
>> software 65816.
>Did this actually have any code for the 65C02 emulator? My project is just
>doing NMOS opcodes.
Yep it did. Are you interest (all the text commentary is in German
though...)
>> I did have some questions about the actually code you used:
>> 1) what did your decode routine look like. How did decode the op code and
>Well, going back to the vector table,
>I just took the opcode, shifted it left, and used that as an index to get
>the vector to the servant routine (obviously adding 256 if the high bit
>were set), and then did an indirect JMP.
Sorry, but the bit-banging part of my brain is on holidays....
so:
clc
lda (opcode),y ;y=0)
asl ; two bytes per JMP vector
sta jmpvector
bcc +
....
sta jmpvector+1
+
jmp(jmpvector)
????
or something like that?
Regards,
- Nick
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