Employed to hold temporarily the righthand instruction from a word in memory.

Contains the address of the next instruction pair to be fetched from memory.

Employed to hold temporarily operands and results of ALU operations.

The IAS operates by repetitively performing an instruction cycle: …. steps

.....is smaller, cheaper, and generates less heat than a vacuum tube, can be used in the same way as a vacuum tube to construct computers

Memory arrays are built as an array of byte cells

Each cell stores 1 byte of data.

Specified by their size (depth x width) and the number and type of ports

All memories have …. Ports

Each port gives read and/or write access to …… memory address

Single ported memories can access several addresses simultaneously

Each memory location has the same address

Memory address usually starts at zero

An address is represented by an signed integer

A word addressable memory: each word has its own address

Used only as a temporary storage

Volatile, it loses its data when the power is turned off

RAM is used in embedded systems or any systems where the programming doesn’t need to change.

Must be provided with constant power supply. If the power is interrupted, then the data are lost

the data and instructions in PROM (Programable ROM) can be changed

in ......no special tools are required for erasure and you can erase only portions of the chip, one
byte at a time.