Memory

Memory

1. what is memory ? Memory is a pretty fundamental part of a computer. it contains all the instructions that the CPU follows. Without memory, a computer wouldnt know what to do with itself

2. RAM

   • RAM (Random Access Memory) is used as the main memory in a computer it can be read and written to. RAM is volatile.
   • The main memory is where all data, files and programs are stored while they're being used
   • When a computer boots up, the operating system is copied from secondary storage to RAM.
   • When software applications, documents and files are opened, they are copied from secondary storage to RAM. they stay in Ram until the files or applications are closed
   • RAM is slower than the CPU cache, but way faster than secondary storage

3. Volatile and non volatile memory

   • Volatile memory is temporary memory. It requires power to retain it's data
   • Non volatile is permanent memory - it keeps its contents even when it has no power

4. Virtual Memory

   • Virtual Memory is Secondary storage used as extra RAM
     • Computers have a limited amount of RAM. As applications are opened, RAM fills with data.
     • When RAM is full, the computer needs somewhere else to put applications data. It moves data that hant been used recently to a location on secondary storage known as virtual memory
     • Virtual memory may be needed if there are too many applications open at once, or if a particularly memory-intensive applications is being used
     • If the CPU needs to read data stored in virtual memory, it must move the data back to RAM. This is slow as data transfer rates are much slower on secondary storage than RAM
     • Using virtual memory can make a computer slow to respond when switching between applications or using a memory-intensive applications .

5. ROM

   • ROM tells the CPU how to Boot up
     • ROMS (read only memory) is on volatile memory. As it says on the tine it can only be read, not written to
     • ROM comes on a small, factory-made chip build into the motherboard.
     • It contains all the instructions a computer needs to properly boot up. These instruction are called the BIOS (basic input output system)
     • As soon as the computer is powered on, the CPU reads the instructions from ROM. This tells the CPU to perform slef checks and sets up the computer e.g. tests the memory is working OK, see what hardware is present and copy the operating system into RAM
     • Although the CPU can any read ROM, it is possible to update 'flash' the BIOS on a ROM chip