Word Length

What do you mean by Fixed Word-Length and Variable Word-Length Memory?

Ì Storage space is always multiple of word-length.

Ì Faster in speed of calculation than variable word-length memory.

Ì Normally used in large scientific computers for gaining speed of calculation.

  

Ì Storage space is always multiple of word-length.

Ì Faster in speed of calculation than variable word-length memory.

Ì Normally used in large scientific computers for gaining speed of calculation.

Computer Register

What is Register?              

£  Special memory units, called registers, are used to hold information on a   temporary basis as the instructions are interpreted and executed by the CPU.

£  Registers are part of the CPU (not main memory) of a computer.

£  The length of a register, sometimes called its word size, equals the number of bits it can store.

Sl.No	Name Of Register	Function
1.	Memory Address Register (MAR)	Holds address of the active memory location.
2.	Memory Buffer Register (MBR)	It holds the contents of the memory word read from, or written in, memory.
3.	Program Counter (PC)	Holds address of the next instruction to be executed
4.	Accumulator (A or AC)	Holds   data   to   be   operated   upon, intermediate results, and also the final results. It is used during the execution of the most instruction.
5.	Instruction Register (IR)	It holds the current instruction that is being executed. The address part of the instruction is sent to the MAR and operation part is sent to the control section where it is decoded and signals are generated to carry out the specific task.
6.	Input / Output Register     (I / O)	This register is used to communicate with the Input/Output devices.