Opcode ESC

CPU: 8086...80386, any Hybrid 486.
Type of Instruction: User

Instruction: ESC Number,R/M

Description: This Instruction uses for Link with External Coprocessors
Such as NPX. External Coprocessors look at command sequence
at get ESC. CPU give Memory Operand sending to A-bus EA
doing pseudo-read operation.
{ If 2nd Operand is Register then Do Nothing,
If 2nd Operand is Memory then set EA (Effective Address)
in Address Bus }
First operand is Part of Command that Ext. coprocessors get.

Flags Affected: None

Example: ESC 0Fh,DX means FSQRT

Note: ESC mnemonic was used for 8086 CPU, later all were used alternative
mnemonic for cooprocessor instructions, such as FSQRT.


Physical Form:
COP (Code of Operation) : <1101 1xxx> Postbyte

Clocks: ESC n,Reg ESC n,Mem8/Mem16
8088: 2 8/12+EA
286: 9-20 9-20
386: N/A N/A
486: N/A N/A

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