MOS Technology 6502
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| General information | |
|---|---|
| Launched | 1975 |
| Common manufacturer(s) | |
| Performance | |
| Max. CPU clock rate | 1 MHz to 3 MHz |
| Data width | 8 bits |
| Address width | 16 bits |
| Architecture and classification | |
| Instruction set | 6502 |
| History | |
| Predecessor(s) | Motorola 6800 |
| Successor(s) | |
The MOS Technology 6502 is an 8-bit processor based off the Motorola 6800. The 6502 was singlehandedly responsible for the home computing revolution, allowing for the development of some of the most influential home computers of the era, including Commodore 64.
Design
Registers
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The 6502, just like the 6800, has a limited set of registers including a single 8-bit accumulator (A), two 8-bit general registers (X and Y), an 8-bit stack pointer (SP) and a 16-bit program counter (PC).
Flags
The processor maintains an internal status register for storing bit flags representing the state of arithmetic and logic operations.
- Negative (N), set if the result is negative.
- Overflow (V), set if .
- Break (B), set if .
- Decimal (D), set if .
- Interrupt disable (I), set if .
- Zero (Z), set if the result is zero.
- Carry (C), set if the last addition operation resulted in a carry, or the last subtraction operation resulted in a borrow.