Summary Introduction to computer application

TOPIC 13
TYPES OF MEMORY
A. Read Only Memory (ROM)
This memory is used to store programmed instructions and data permanently or semi-
permanently. Data and instructions stored in ROM are those required to remain unchanged for
a long time.
Types of ROM
Mask Read Only Memory (MROM)
Once contents are written on it by the manufacturer, it cannot be changed.

Programmable Read Only Memory (PROM)
This allows the user to alter it only once after the content is written on it.


Erasable Programmable Read Only Memory (EPROM)
The contents stored in this memory can be erased by exposing them to ultra-violet light
and then re-programmed for another use.
Electrically Erasable Programmable Read Only Memory (EEPROM)
This memory can be erased and reprogrammed using electricity.


Characteristics of ROM
 Can only be read but not written on.
 It’s non - volatile.
 Stores permanent instructions from the manufacturer.


B. Random Access Memory (RAM)
It’s called random access memory because its content can be read directly regardless of the
sequence in which it was stored.
Types of RAM
Static RAM (SRAM)
It’s a very fast memory and holds its content as long as there is power.
Dynamic RAM (DRAM)