Memory in Computer Systems

Memory in Computer Systems

1. Refers to the components that store (or remember) instructions and data.

2. Types of Memory

   • Cache
     • Small amount of memory which is a part of the CPU - closer to the CPU than RAM. It is used to temporarily hold instructions and data that the CPU is likely to reuse.
   • RAM
     • Used in the Computer's Main Memory. Not really random, it refers to the fact that it can be stored anywhere. Main purpose of RAM is to act as temporary storage for programs and data, just for the duration of that program. Once the program has finished and is closed ,it is no longer held in main memory. Volatile and has a quicker access speed than virtual memory but slower than cache.
   • Virtual Memory
     • Sometimes there isn't enough main memory for all the programs that need to run. Computers can be configured so that part of the hard disk behaves like main memory - virtual memory. Slowest access speed than all other main memory storages. This is because the processor takes longer to swap data between virtual memory and main memory than executing the program. Volatile.
   • ROM
     • You cannot write over the contents once it has been created. It is also non-volatile; you can leave the computer switched off for months and it will still start up as soon as it has power again. ROM is usually found in computers for boot up instructions and on bought software CDs.