3. What is register? A register is one of a small set of data
holding places that are part of a
computer processor .
A register may hold :
❖ A computer instruction
❖ A storage address
❖ Or any kind of data (such as a bit
sequence or individual
characters)
4. Types of registers I. Memory Buffer Register (MBR) :
A. Used to receive a word from main
memory or i/o device
II. Memory Address Register (MAR) :
A. Specifies the address in memory
III. Instruction Register (IR) :
A. Contains 8 bit opcode instruction being
executed.
IV. Program Counter (PC) :
A. Holds the address of the next
instruction
V. Accumulator (AC) :
A. Processor register , it holds temporary
operands and results of ALU operation.
5. 1PC
MAR
MDR
AC
1
LOAD 5
10
1. LOAD 5
2. ADD 6
3. STO 7
4.
5. 10
6. 15
7. 25
8.
ADDRESS BUS
DATA BUS
5
10
2
2
ADD 6
25
6
15
3
3
STO 7
7
25
Fetch-execute cycle and role of registers
CPU
Memory
6. ❖ This register is a most important part of CPU.
❖ Processor register is fast storage device.
❖ A processor register is a quickly accessible location available to
a computer's central processing unit (CPU).
Conclusion :
