4.4 Operation of the CPU

For each instruction

1.         The control unit fetches the instruction from primary storage.

2.         The control unit decodes the instruction and makes the data available to the arithmetic logic unit. This is called instruction ir i-time

3.         The arithmetic logic unit performs the operations on the data.

4.         The control unit places the result of the operation into primary storage or a register. This is called execution or e-time.

 

 

Computers are fast at executng instructions. The speed of a computer can be measured by

1. Clock speed is the number of cycles per second and is measured in megahertz (MHz)
2. MIPS (million instructions per second) and FLOPS (floating point operations) are a more accurate way of measuring the speed of the computer.

Write out the sentence and fill in the missing word

 

The ????? executes a computer program

Most computers execute only ????? instruction at a time

Before an instruction is executed, the instructions and data are placed in ?????

????? fetches the instructions from the primary storage

The control unit decodes the instructions and makes them available to the ?????

The arithmetic logic unit performs the operations on the ?????

The ????? cycle is the combination of i-time and e-time

Most computers execute an instruction measured in ?????

Tasks are performed more quickly by microprocessors with higher ?????

Computer speed for more powerful computers is measured in ????? and FLOPS