MC80287 データシートの表示（PDF） - Intel

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MC80287

80-BIT HMOS NUMERIC PROCESSOR EXTENSION

Intel 

M80287

FUNCTIONAL DESCRIPTION

The M80287 Numeric Processor Extension (NPX)

provides arithmetic instructions for a variety of nu-

meric data types in M80286 20 systems It also exe-

cutes numerous built-in transcendental functions

(e g tangent and log functions) The M80287 exe-

cutes instructions in parallel with an M80286 It ef-

fectively extends the register and instruction set of

an M80286 10 system for existing M80286 data

types and adds several new data types as well Fig-

ure 3 presents the program visible register model of

the M80286 20 Essentially the M80287 can be

treated as an additional resource or an extension to

the M80286 10 that can be used as a single unified

system the M80286 20

The M80287 has two operating modes similar to the

two modes of the M80286 when reset M80287 is in

the real address mode It can be placed in the pro-

tected virtual address mode by executing the

SETPM ESC instruction The M80287 cannot be

switched back to the real address mode except by

reset In the real address mode the M80286 20 is

completely software compatible with M8086 88 20

Once in protected mode all references to memory

for numerics data or status information obey the

M80286 memory management and protection rules

giving a fully protected extension of the M80286

CPU In the protected mode M80286 20 numerics

software is also completely compatible with

M8086 20 and M8088 20

The M80287 has two operating modes similar to the

two modes of the M80286 When reset M80287 is

in the real address mode It can be placed in the

protected virtual address mode by executing the

SETPM ESC instruction The M80287 cannot be

switched back to the real address mode except by

reset In the real address mode the

M80286 M80287 is completely software compatible

with M8086 M8087 and M8088 M8087

Once in protected mode all references to memory

for numerics data or status information obey the

M80286 memory management and protection rules

giving a fully protected extension of the M80286

CPU In the protected mode M80286 M80287 nu-

merics software is also completely compatible with

M8086 M8087 and M8088 M8087

Figure 3 M80286 20 Architecture

271029 – 3

3

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