Re: 6502 illegal opcodes questions

[heuser.marcus@freenet.de]

There are some discrepancies between the different info files floating
around the net. Some opcodes go by different names or have a different
meaning. I've found at least three different descriptions of the $93
opcode.

Here are without any claim of validity excerpts from "6502 Undocumented
Opcodes v3.0" by Freddy Offenga:

===

"The timing values (clock cycles) from all the opcodes were compared
with
the values on the list by Adam Vardy. There were no differences.

The addressing modes for the "DOP" (double nop) and "TOP" instructions
were copied from Craig Taylor's list. The reason for this is that the
different addressing modes explain the differences in the timing
values. "

===

DOP (NOP) [SKB]
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
No operation (double NOP). The argument has no significance.
Status flags: -

Addressing  |Mnemonics  |Opc|Sz | n (cycles)
------------|-----------|---|---|---
Zero Page   |DOP arg    |$04| 2 | 3
Zero Page,X |DOP arg,X  |$14| 2 | 4
Zero Page,X |DOP arg,X  |$34| 2 | 4
Zero Page   |DOP arg    |$44| 2 | 3
Zero Page,X |DOP arg,X  |$54| 2 | 4
Zero Page   |DOP arg    |$64| 2 | 3
Zero Page,X |DOP arg,X  |$74| 2 | 4
Immediate   |DOP #arg   |$80| 2 | 2
Immediate   |DOP #arg   |$82| 2 | 2
Immediate   |DOP #arg   |$89| 2 | 2
Immediate   |DOP #arg   |$C2| 2 | 2
Zero Page,X |DOP arg,X  |$D4| 2 | 4
Immediate   |DOP #arg   |$E2| 2 | 2
Zero Page,X |DOP arg,X  |$F4| 2 | 4 

===

bye
Marcus