## ALP Programming Guide and Reference

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### Description

The above forms of the MOV instruction store or load the DR0, DR1, DR2, DR3 , DR6 and DR7 debug resisters to or from a general purpose register.

Thirty-two bit operands are always used with these instructions, regardless of the operand-size attribute.

When the DE (Debug Extension) bit in CR4 is clear, MOV instructions using debug registers operate in a manner that is compatible with Intel386 and Intel486 CPUs. References to DR4 and DR5 refer to DR6 and DR7, respectively . When the DE bit in CR4 is set, attempts to run MOV instructions using DR4 and DR5 result in an Undefined Opcode (#UD) exception.