This instruction is a prefix that causes the CPU assert bus lock signal during the execution of the next instruction.
Used to avoid two processors from updating the same data location.
The 286 always asserts lock during an XCHG with memory operands.
This should only be used to lock the bus prior to XCHG, MOV, IN and OUT instructions.
Usage:
LOCK ; LOCK ; (386+ prefix)
Modifies flags:
none
| Clocks | Size | |||||
|---|---|---|---|---|---|---|
| Operands | 808x | 286 | 386 | 486 | Bytes | |
| none | 2 | 0 | 0 | 1 | 1 | |