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X-Hacker.org- iAPx86 - <b>esc escape flags: not altered</b>
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ESC Escape Flags: Not altered
ESC
ESC lets you send instructions to an external coprocessor on the
system bus. On the 80386 and earlier processors, this was usually
a floating-point chip called a numeric (or math) coprocessor. The
8086 and 8088 work with an Intel 8087 math coprocessor; the 80286
and 80386 work with an 80287 or 80387 coprocessor. The 80486 DX
has a math coprocessor, called the Floating-Point Unit (FPU), on
the chip.
Note: In order to synchronize with the 8087 math
coprocessor, WAIT instructions must precede all ESC
instructions. The 80286+ has automatic instruction
synchronization, hence WAITs are not needed.
Opcode
The opcode for ESC begins with the 5-bit sequence "11011b". This
sequence indicates that the rest of the opcode is an instruction
meant for a coprocessor, as opposed to an instruction meant for
the CPU.
See Also: HLT WAIT LOCK
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