IGCSE ICT 0417 - Types and Components of Computer Systems

Internal Memory

Internal memory refers to the memory that is built into the computer system. It is used to store data and instructions that the computer is actively using. Internal memory is generally faster than external memory.

Types of Internal Memory

There are two main types of internal memory: Random Access Memory (RAM) and Read-Only Memory (ROM).

Random Access Memory (RAM)

RAM is a type of volatile memory, meaning that the data stored in RAM is lost when the power is turned off. RAM allows the computer to quickly access any data stored in it. It is used to store the operating system, applications, and data that are currently being used by the computer.

Characteristics of RAM:

• Volatile: Data is lost when power is off.
• Fast Access: Allows quick reading and writing of data.
• Used for active data: Stores data and instructions the CPU is currently working with.
• Types of RAM:
• DRAM (Dynamic RAM): Requires periodic refreshing to retain data.
• SRAM (Static RAM): More expensive but faster and doesn't require refreshing.

Feature	Description
Volatility	Volatile (data lost when power is off)
Access Speed	Very Fast
Cost	Relatively expensive
Usage	Stores active data and running programs

Read-Only Memory (ROM)

ROM is a type of non-volatile memory, meaning that the data stored in ROM is retained even when the power is turned off. ROM typically contains the instructions that are needed to start the computer, known as the BIOS (Basic Input/Output System) or UEFI (Unified Extensible Firmware Interface).

Characteristics of ROM:

• Non-Volatile: Data is retained even when power is off.
• Slower Access: Accessing data is slower than RAM.
• Used for startup instructions: Contains the instructions needed to boot the computer.
• Types of ROM:
• Mask ROM: Data is programmed during manufacturing and cannot be changed.
• PROM (Programmable ROM): Can be programmed once after manufacturing.
• EPROM (Erasable Programmable ROM): Can be erased and reprogrammed using ultraviolet light.
• EEPROM (Electrically Erasable Programmable ROM): Can be electrically erased and reprogrammed.

Feature	Description
Volatility	Non-Volatile (data retained when power is off)
Access Speed	Slower than RAM
Cost	Relatively inexpensive
Usage	Stores boot instructions (BIOS/UEFI)

Comparison of RAM and ROM

The following table summarizes the key differences between RAM and ROM:

Feature	RAM	ROM
Volatility	Volatile	Non-Volatile
Access Speed	Fast	Slower
Cost	Expensive	Inexpensive
Usage	Stores active data and programs	Stores boot instructions