Cache Memory and Register Memory

M1-R5.1 & CCC · Chapter 1: Introduction to Computer · 3 min read

Cache Memory

  • Cache memory is a  very small and very fast memory placed b/w CPU and main memory (RAM).                   
  • Cache is faster than main memory, so it improves the overall speed of the computer.                           
  • It works as a high-speed buffer b/w C.P.U. and main memory (RAM).
  • It is used to temporarily store very active data and instructions during processing. 
  • It stores frequently used data and instructions temporarily so the CPU can access them faster.
  • Access time of a cache memory is 15-25 nanosecond, while main memory takes about 25 nanoseconds.
  • Many Computer Systems are designed to have two Separate Cache memories- 

            1. Instruction Cache 

            2. Data cache

  • The instruction cache is used for storing program instructions and the data cache is used for Storing data.
  • Many computer systems are also designed to have multiple levels of caches such as- L1,L2,L3I

Register Memory

  • "Register memory" usually refers to a type of computer memory used in processors (CPUs). 
  • Register memory is a small, fastest type of memory used inside the CPU.
  • These registers are used to hold information on a temporary basis during instruction execution.
  • All the instructions are read and run by the CPU using these registers.
  • The size of registers is very small (measured in bits),but they work very quikly.

Common Types of Registers:

1)Memory Address Register (MAR): 

  1. It holds the address of active memory location.

2)Memory Buffer Register(MBR)/ MDR( Memory Data Register):

  • Temporarily holds data being transferred to or from memory.

3)Program Counter Register(PCR):

  • Holds the address of the next instruction to be executed.

4)Accumulator Register(ACC): 

  • Used in arithmetic and logic operations.

5)Instruction Register (IR):

  • Holds the current instruction that is being executed by the CPU.

6)Input/Output Register( I/O Register):

  • Temporarily holds data going to or coming from an I/O device.

7)Decoder: 

  • It has a necessary circuit way  to decode and interpret the meaning of each and every instruction supported by the CPU.

8)General Purpose Registers: 

  • Temporarily hold data during execution.