INTEL387TMDX 데이터 시트보기 (PDF) - Intel

부품명

상세내역

일치하는 목록

INTEL387TMDX

Intel387™ DX MATH COPROCESSOR

Intel 

Intel387TM DX MATH COPROCESSOR

2 3 4 INSTRUCTION AND DATA POINTERS

Because the MCP operates in parallel with the CPU

any errors detected by the MCP may be reported

after the CPU has executed the ESC instruction

which caused it To allow identification of the failing

numeric instruction the Intel386 DX Microprocessor

and Intel387 DX Math CoProcessor contains two

pointer registers that supply the address of the fail-

ing numeric instruction and the address of its numer-

ic memory operand (if appropriate)

The instruction and data pointers are provided for

user-written error handlers These registers are ac-

tually located in the Intel386 DX CPU but appear to

be located in the MCP because they are accessed

by the ESC instructions FLDENV FSTENV FSAVE

and FRSTOR (In the 8086 8087 and 80286 80287

these registers are located in the MCP ) Whenever

the Intel386 DX CPU decodes a new ESC instruc-

tion it saves the address of the instruction (including

any prefixes that may be present) the address of

the operand (if present) and the opcode

The instruction and data pointers appear in one of

four formats depending on the operating mode of

the Intel386 DX Microprocessor (protected mode or

real-address mode) and depending on the operand-

size attribute in effect (32-bit operand or 16-bit oper-

and) When the Intel386 DX Microprocessor is in vir-

tual-8086 mode the real-address mode formats are

used (See Figures 2 3 through 2 6 ) The ESC in-

structions FLDENV FSTENV FSAVE and FRSTOR

are used to transfer these values between the In-

tel386 DX Microprocessor registers and memory

Note that the value of the data pointer is undefined if

the prior ESC instruction did not have a memory op-

erand

31

00000

32-BIT PROTECTED MODE FORMAT

23

15

7

RESERVED

CONTROL WORD

RESERVED

RESERVED

STATUS WORD

TAG WORD

IP OFFSET

OPCODE 10 0

CS SELECTOR

DATA OPERAND OFFSET

RESERVED

OPERAND SELECTOR

0

0

4

8

C

10

14

18

Figure 2 3 Protected Mode Intel387TM DX MCP Instruction and

Data Pointer Image in Memory 32-Bit Format

12

12

Share Link: