Download 10. Registers in Micro Processor

Computer Architecture
CST 250
Microprocessor Registers
Prepared by:Omar Hirzallah
Contents
General Purpose Registers
Index Registers
Segment Registers
Special Registers
Programming Languages
The Registers in CPU
Processor uses a very high speed small in size memory device
during data processing which are called registers
C.P.U
Registers
General
Purpose
Registers
Index
Registers
Segment
Registers
• Accumulator
• Stack Pointer
• Code Segment
•Base
•Base Pointer
• Data Segment
•Count
•Source Index
• Stack Segment
•Data
•Destination Index
• Extra Segment
Special
Registers
• Instructions
Pointer
• Flags
Register
General Purpose Registers:
Accumulator (AH, AL, AX, EAX):
It accumulates the results from mathematical calculations and can
be used for data movement. AH 8 bits, AL 8 bits, AX 16 bits,
EAX 32 bits
Base (BH,BL,BX, EBX): It points to memory locations and it can
be used for data movement and arithmetic. (Points to data in the
Data Segment) BH 8 bits, BL 8 bits, BX 16 bits, EBX 32 bits
Count (CH, CL, CX, ECX): This counter is used typically for loops.
It can be automatically incremented or decremented. CH 8 bits,
CL 8 bits, CX 16 bits, ECX 32 bits
Data (DH,DL, DX, EDX): It is used in calculations. It is also used
significantly for multiply / divide operation. DH 8 bits, DL 8 bits,
DX 16 bits, EDX 32 bits
C.P.U Registers
INDEX REGISTERS:
Stack Pointer (SP, ESP): It points to the location of
the stack (points to the end of the stack). SP 16 bits,
ESP 32 bits
Base Pointer (BP, EBP): It is also used to point inside
the stack. It is used to access the sub routine data. BP
16 bits, EBP 32 bits
Source Index (SI, ESI): It is used for string operations
(points to the source). SI 16 bits, ESI 32 bits
Destination Index Register (DI, EDI): It is used for
string operations (points to the destination). DI 16 bits,
EDI 32 bits
SEGMENT REGISTERS (ALL 16 bits)
 Code Segment (CS): It points to the memory
area where program's instructions are stored.
 Data Segment (DS): It points to the memory
area where program's data is stored.
 Stack Segment (SS): It points to the memory
area where stack is stored.
 Extra Segment (ES): It can be used to point to
additional data segments, if necessary.
SPECIAL REGISTERS:
 SPECIAL REGISTERS:
 Instruction Pointer (IP, EIP): It points to the next
instruction that the processor is going to
execute. (also called program counter)
 Flags Register (Flag, Eflag): It contains
individual bits set by different operations.
 CF  Carry
 OF  Overflow
 ZF  Zero
 SF  Sign
Programming Languages:
There are basically two types of programming languages:
1.
High Level Languages
(Pascal, Basic, Cobol, C, Fortran etc.)
2.
Low Level Languages
(Assembly)
Each processor has a set of assembly instructions called
“Instruction Set”.
CISC stands for Complex Instructions Set Computers
RISC stands for Reduced Instructions Set Computers
Assembly Language
Assembler
Machine Language