Register for under graduation program

1. Computer
Architecture
Topic: Register

2. To temporarily store data and instructions, the CPU has high-speed special-purpose
storage devices called ‘Registers’.
➢ Register is the high-speed memory location that is built directly
into the ALU part of the CPU.
➢ It holds data and instructions temporarily that are currently being
processed.
➢ The computer loads instruction and data from main memory into
the registers just before processing, which helps the computer process faster.
The size of the registers, which is sometimes called the word size, indicates the
amount of data with which the computer can work at any given time.
➢ The bigger the word size, the more quickly the computer can
process a set of data.
Register

3. 01
02
03
04
Memory Address Register (MAR)
Memory Buffer Register (MBR)
Program Control Register (PC)
Accumulator Register (AC)
05 Instruction Register (IR)
06 Input/output Register (I/O)

4. ❖ It holds the address of the active memory
location.
❖ The address is loaded from the Program
Control Register (PC) when an instruction is
read from memory.
Memory Address Register (MAR)

5. ❖ This register acts as a buffer between the CPU and the
memory
❖ It holds the contents of the memory word read from, or written
in memory.
❖ An instruction word placed in this register is transferred to the
Instruction Register (IR)
❖ A data word placed in this register is accessible for operation
with the Accumulator Register (AC) or for transfer to I/O
Register.
Memory Buffer Register (MBR)

6. ❖ It holds the address of the next instruction to be executed.
❖ [Normally, the instructions of a program are stored in
consecutive memory locations, and read and executed in
sequence, unless a branch instruction is encountered].
❖ For a branch instruction, the address part of the branch
instruction is transferred to the Program Control Register (PC) to
become the address of the next instruction.
Program Control Register (PC)

7. ❖ It holds:
▪ The initial data to be operated upon.
▪ The intermediate results.
▪ And the results of processing.
❖ It is used during the execution of most instructions.
❖ The results of arithmetic operations are returned to the
Accumulator Register (AC) for transfer to main memory, through
the Memory Buffer Register (MBR).
❖ In many computers, there are more than Accumulator registers.
Accumulator Register (AC)

8. ❖ It holds the current instruction, which is being executed.
❖ As soon as the instruction is stored in this register, the
operation part and the address part of the instruction are
separated.
❖ The address part of the instruction is sent to Memory
Address Register (MAR), while its operation part is sent to the
Control Unit, where it is decoded, and interpreted for the action
to be performed.
Instruction Register (IR)

9. ❖ It is used to communicate with the input/output device.
❖ All input information, such as instructions and data, are
transferred to this register by an input device.
❖ Similarly, all output information, to be transferred to an output
device, are found in this register.
❖ The registers discussed above can be of special purpose or
general purpose.
❖ Special purpose registers are dedicated for certain functions
only and are generally not under program control.
❖ General purpose registers can be used for several functions
under program control. They are convenient store for holding
data which is currently processed by the ALU, for storing some
data temporarily and also for storing intermediate results.
Input/output Register (I/O)

10. Prepared by:
Ankon Gopal Banik
Front End Developer | WWF (Web With Friends)
m: +8801771981989
p: 027730402
e: agbanik2081@outlook.com
75-B, Kyetpara, Dhamrai, Dhaka, Bangladesh
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11. Thank you