This indicates what registers are used for what purposes on each of the processors supported by Free Pascal. It also indicates which registers can be used as scratch registers.
| Generic register name | CPU Register name |
| accumulator | EAX |
| accumulator (64-bit) high / low | EDX:EAX |
| float result | FP(0) |
| self | ESI |
| frame pointer | EBP |
| stack pointer | ESP |
| scratch regs. | N/A |
| OS_128 type (128 bit integer) | RDX:RAX |