Main Memory, RAM & ROM Flashcards

All 10 cards in this deck

What is main memory?

Any memory that the CPU can access directly, apart from cache and registers. RAM and ROM are main memory.

Why does a computer need main memory?

So the CPU can quickly access the instructions and data of the programs currently being run.

What is RAM?

Volatile main memory: it can be read from and written to, and loses its contents when the power is switched off.

What is ROM?

Non-volatile main memory: it keeps its contents when the power is switched off, and can be read from but not written to.

What does RAM hold while a computer is running?

The operating system and the programs and documents currently open/in use.

What is usually stored in the ROM of an embedded system?

The start-up instructions and the firmware: the program that controls the device, which rarely or never needs to change.

Give two differences between main memory and secondary storage.

Main memory is faster and directly accessible by the CPU; secondary storage is slower, non-volatile, not directly accessible by the CPU and has a much larger capacity.

True or false? A program stored on a hard disk must be loaded into main memory before the CPU can run it.

True. The CPU fetches its instructions and data from main memory, not directly from secondary storage.

What is the purpose of ROM in a general purpose computer?

It stores the BIOS: the start-up (boot) instructions the CPU runs when the computer is switched on, which check the hardware and load the operating system into RAM.

Why are a computer's start-up instructions stored in ROM rather than RAM?

ROM is non-volatile, so the instructions are still there when the power comes on. RAM loses its contents when switched off.