AQA A-Level Computer Science 4.7 Computer organisation and architecture overview quiz quiz

RAM is non-volatile permanent storage, whereas ROM is the volatile working memory the processor uses

RAM is volatile working memory; ROM is non-volatile and holds boot firmware

ROM can be freely overwritten during normal use, while RAM keeps its contents permanently

RAM and ROM are functionally identical and interchangeable forms of memory

The data bus

The control bus

The address bus

The system bus

Programs are kept permanently on secondary storage and are executed directly from the disk without being loaded

Programs are physically hard-wired into the processor at manufacture and can never afterwards be changed

Each separate program requires its own dedicated processor in order to be fetched and executed

Program instructions are stored in main memory alongside the data and fetched and executed one at a time

Separate buses for instructions and data let both be fetched at the same time

It is far simpler and cheaper to build because it requires only one bus and one memory

It removes the need for any main memory by storing everything in the processor

It uses a single shared bus for both instructions and data, reducing the wiring needed

The accumulator

The program counter (PC)

The memory data register (MDR)

The current instruction register (CIR)

The full instruction itself, decoded ready for the execute stage

The result of the most recent arithmetic calculation

The address held in the program counter

The current contents of the accumulator register

Lowering the clock speed so each cycle lasts longer

Fitting a narrower data bus that carries fewer bits per transfer

Removing processing cores to free up power

A larger, faster cache

The actual value to be used

The memory address of the value

A register number

The next instruction

Mantissa and exponent

Opcode and operand

Address bus and data bus

Cache and register

It contains spinning platters and read-write heads that are easily damaged by movement

It has slower read and write speeds than a traditional magnetic hard disk drive

It is more expensive per byte and has a limited number of write cycles

It is volatile and loses all stored data the moment power is removed

RAM operates too quickly for the processor to keep up with during normal use

Secondary storage offers much faster read and write access speeds than the main RAM does

RAM can only be written to and its contents can never afterwards be read back

RAM is volatile and loses data when power is off, so a non-volatile store is needed