Compilation study (ii)--8086CPU

One, 8086CPU 1, microprocessor

(1) Micro-control machine: Also known as single-chip microcomputer

(2) DSP chip: Digital signal processing chip

(3) Embedded microprocessor

(4) Universal microprocessor: PC Station, workstation, server using the processor

2. Internal structure:

(1) Bus interface Unit (BIU):

A. Responsible for data transmission and instruction Reading

B, the execution unit to the instruction machine code decoding

C, coordinated control of the components in the chip

(2) Execution Unit (EU): Perform operation

3, 8086 registers

(1) General Register:

A, 8 general-purpose registers: AH,AL,BH,BL,CH,CL,DH,DL

B, 2 variable address registers: Si,di

C, 2 pointer registers: BP,SP

These four registers can only be operated in 16-bit, primarily for staging data or addresses

(2) Segment Register:

Segment address for primary storage-based segment management

(3) Control register:

The instruction pointer IP is actually a 16-bit plus counter that always points to the address of the next command to execute.

4. Flag register in Control register

(1) Control mark:

DF: Direction sign

IF: Interrupt Flag

TF: Single-step flag or trap flag

(2) Condition Mark position

PF: Parity flag: The lower 8 bits of the calculated result, if the number of 1 is an even number, then pf=1, otherwise pf=0

ZF: 0 Flag bit: Calculation result is 0,zf=1, otherwise zf=0

AF: Auxiliary carry/Borrow flag bit: calculation result D3 to D4 carry or borrow, then af=1, otherwise af=0.

CF: Carry/Borrow flag bit: the highest bit of the calculated result forward bit or borrow, then cf=1, otherwise cf=0

SF: Symbol flag bit: Calculate the demerit is negative, sf=1, otherwise sf=0, is actually the highest bit of the computer (complement)

Of: Overflow flag bit: The calculation result exceeds the symbol number of the complement number of expression range: of=1, otherwise of=0. Used to calculate addition and subtraction errors.

(3) method of judging the mark of the:

Subtraction is the same.

Compilation study (ii)--8086CPU