For questions on the MOS Technology 650x family of processors. For questions about the 6502 use the "6502" tag.
Questions tagged [mos-650x]
16 questions
15
votes
2 answers
What is a use case for the JAM instruction on the MOS Technology 650x family of processors?
I was reading about undocumented opcodes for the 650x family of processors and discovered JAM, an instruction "which simply causes the CPU to freeze, requiring a hardware reset or power cycle to restart."1
Was this instruction ever used in…
JAL
- 9,502
- 14
- 57
- 120
10
votes
2 answers
How does the 6502 implement its branch instructions?
The 6502's decode ROM takes an input which tells it when to start the next instruction. In the case of something like an INX or LDA #7F, it is obvious that once the output from the ALU has been latched in the destination register, the ROM may issue…
Omar and Lorraine
- 38,883
- 14
- 134
- 274