Just wanted to mention something -- this page has a couple of minor mistakes. (And I'm not sure who to contact about it
http://nesdev.com/6502.txt
The STA section has a couple of incorrect opcode numbers. (Same incorrect numbers are in the by-opcode-number listing, though they're in the right spot.)
I noticed this after being tripped up for a while when decoding some instructions incorrectly.
(Another opcode map for reference: http://nparker.llx.com/a2/opcodes.html )
Thanks all! Cheers
http://nesdev.com/6502.txt
The STA section has a couple of incorrect opcode numbers. (Same incorrect numbers are in the by-opcode-number listing, though they're in the right spot.)
Code:
STA STA Store accumulator in memory STA
Operation: A -> M N Z C I D V
_ _ _ _ _ _
(Ref: 2.1.2)
+----------------+-----------------------+---------+---------+----------+
| Addressing Mode| Assembly Language Form| OP CODE |No. Bytes|No. Cycles|
+----------------+-----------------------+---------+---------+----------+
| Zero Page | STA Oper | 85 | 2 | 3 |
| Zero Page,X | STA Oper,X | 95 | 2 | 4 |
| Absolute | STA Oper | 80 | 3 | 4 | <-- opcode should be 8D
| Absolute,X | STA Oper,X | 90 | 3 | 5 | <-- opcode should be 9D
| Absolute,Y | STA Oper, Y | 99 | 3 | 5 |
| (Indirect,X) | STA (Oper,X) | 81 | 2 | 6 |
| (Indirect),Y | STA (Oper),Y | 91 | 2 | 6 |
+----------------+-----------------------+---------+---------+----------+
Operation: A -> M N Z C I D V
_ _ _ _ _ _
(Ref: 2.1.2)
+----------------+-----------------------+---------+---------+----------+
| Addressing Mode| Assembly Language Form| OP CODE |No. Bytes|No. Cycles|
+----------------+-----------------------+---------+---------+----------+
| Zero Page | STA Oper | 85 | 2 | 3 |
| Zero Page,X | STA Oper,X | 95 | 2 | 4 |
| Absolute | STA Oper | 80 | 3 | 4 | <-- opcode should be 8D
| Absolute,X | STA Oper,X | 90 | 3 | 5 | <-- opcode should be 9D
| Absolute,Y | STA Oper, Y | 99 | 3 | 5 |
| (Indirect,X) | STA (Oper,X) | 81 | 2 | 6 |
| (Indirect),Y | STA (Oper),Y | 91 | 2 | 6 |
+----------------+-----------------------+---------+---------+----------+
I noticed this after being tripped up for a while when decoding some instructions incorrectly.
(Another opcode map for reference: http://nparker.llx.com/a2/opcodes.html )
Thanks all! Cheers