Microprocessors 8088 & 8086(1)

8/10/2019 Microprocessors 8088 & 8086(1)

1/16

Types Of Registers


2/16

Types Of Registers There are five types of registers which are used in

microprocessor 8088 & 8086.

1. Data registers2. Segment registers

3. Index registers

4. Pointer registers

5. Flag


3/16

Data Registers Data registers are further divided into four categories

and each category is of 16-bits which can be dividedinto further two parts and each part is of 8-bits. Onepart can be said high which contain higher byte andsecond part can be said lower which contain lowerbyte. The data registers category is following:

1. AX >> Accumulator2. BX>> Base Register

3. CX>> Count register

4. DX>> Data register


4/16

AX-Register This register is known as accumulator.

The accumulator is used for instructions such as

multiplication, division, and some other adjustmentinstruction.

It is considered to be a multipurpose register.

It is divided into further two parts AH and AL.


5/16

BX-Register This register in known as base register.

This register hold the offset address of a location in the

memory system in all versions of microprocessor. It can be divided into further two parts BH and BL.


6/16

CX-Register This register is known as count register.

The loop programs are facilitated by the use of this

register. It serves as a loop counter.

It can be further divided into two parts CH and CL.


7/16

DX-Register This register is known as Data register.

It is used for general purpose register which hold a part

of the result from multiplication and division. This register can also be address memory data.

This register is further divided into two parts DH andDL.


8/16

Segment Register The segment register is used to store address.

An address is generated by the processor, it is added to

the value of one of the segment registers, after thatsegment register is effectively multiplied by 16, or leftshifted four bits, in order to generate the physicaladdress that accesses memory. This gives an effective

address range of 20-bits, or 1-mb, but only 64-kb isaddressable through any segment register at one time,unless we stop to change the contents of that segmentregister.


9/16

Segment Register The segment register is divided into four categories:

1. SS>>Stack segment

2. ES>>Extra segment3. CS>>Code segment

4. DS>>Data segment


10/16

Segment Register Stack register>> It is used for access to stack data.

Extra register>> It is used for access to data during

certain string primitive operations. Code register>> It is used for access to program code.

Data register>> It is used for access to data.


11/16

Index Register They point to memory locations.

They usually have offset address of a memory location.

They are used in arithmetic and other operations. The index register is further divided into two

categories.

1. SI>>Source index

2. DI>>Destination index


12/16

SI-Register This register is known as source index.

This register is used to point to memory locations in

the data segment addressed by DS. By incrementingthe contents of SI, we can easily access consecutivememory locations.


13/16

DI-Register This register is known as destination register.

Its function is same as SI.

There is a class of operation called string operation,that use DI to access memory locations addressed byES.


14/16

Pointer Register Pointer registers are those register which used for

pointing to locations of memory and for stack.

They are further divided into two categories:1. BP>>Base pointer

2. SP>>Stack pointer


15/16

Pointer Registers Stack pointer>> It is used in conjunction with SS for

accessing the stack segment.

Base pointer>> It is used primarily to access data onthe stack. We can also use BP to access data in othersegments.


16/16

FLAGS Register The purpose of FLAGS register is to indicate the status

of the microprocessor. It does this by setting ofindividual bits called flags.

They are further divided into two parts:

1. Status flags

2. Control flags

Microprocessors 8088 & 8086(1)

Documents

Transcript of Microprocessors 8088 & 8086(1)