RAM and ROM nicely explained

A computer fundamentally operates as a collection of switches, each capable of being either 'on' or 'off'. Messages fed into the computer create temporary patterns of these switches in its memory.

Some switches are pre-set at the factory, forming permanent instructions for basic computer functions like loading programs and printing. This section of memory is called Read-Only Memory (ROM) because the computer can read from it but cannot change or write to it.

The other half of the computer's memory is Random Access Memory (RAM). Here, the computer can write temporary messages anywhere it chooses, having 'random access' to this part of its memory. However, these messages disappear when the computer is switched off.

Instead of manually programming messages into RAM, ready-made programs can be loaded from external sources like cassettes or discs. These programs remain in RAM until the computer is turned off, but the original copies on the cassette or disc are retained.

In summary, ROM is permanent, read-only memory that never forgets its instructions. RAM, conversely, is both read and write memory, but it's temporary and loses all its information when the computer is turned off.