1.2 Memory - V2

1.2 Memory - V2

1. Key Words

   • RAM - Random Access Memory
     • Disk Thrashing - When a computers virtual memory subsystem is in a constant state of paging
   • ROM - Read Only Memory
   • CPU - Central Processing Unit
   • Volatile - Gets emptied when the power is turned off
   • Firmware - Permanent Software that is programmed into the ROM
   • Non-Volatile - Doesn't lose the data when the device is turned off
   • BIOS - Basic Input/Output system contains programs to load the hardware
   • Paging - Moving programs from virtual memory to RAM/Cache
   • Backup - To have a second copy of data and software

2. RAM

   • Types Of Ram
     • Dynamic RAM - DRAM Uses a transistor and a capacitor to represent and store a bit of data, the charge needs to be refreshed every few seconds meaning it is slower than static RAM.
     • Static RAM - SRAM Uses a group of transistors combined for each bit of data, they do not lose the charge while in use so SRAM is much faster than DRAM. Sram can be non-volatile when used for flash memory is storage and ROM.
   • Specific instructions that would be in ROM - Values stored cannot be accidentally changed, ROM is always remembered no matter if it is turned on or off

3. Boot Strap - The program which takes the computer through steps that lead up to the loading of the Operating System

   • BIOS - Basic Input Output System The basic firmware that is embedded into the computers ROM chip which is used to start up the computer
   • Firmware - Software that controls a device and is not intended to be changed

4. Volatile - Gets emptied when the power is turned off, for example RAM etc

   • Instructions - A single action/operation that can be performed by a computer processor, for example registers and opcode
     • CPU - The brain of the computer (fetch, decode, execute cycle) that processes program instructions, for example arithmetic calculations etc

5. Virtual Memory

   • Solid
   • Non-Volatile
   • EEPROM
   • Durable, Reliable, Low Cost
   • Used in solid-state media
   • No moving parts
   • Virtual Memory is needed when there is more memory to be used than there is in the system

6. How Virtual Memory Is Implemented

   • Virtual memory is implemented by the virtual memory manager, it creates a file inside of the hard drive, the OS can then address memory, swapping or paging, more data between RAM+Virtual memory, OS moves the data, out of RAM and then stored in virtual memory

7. Three uses for flash memory are: Solid State Drive, Hard Disk, Flash Drive

8. Flash memory is cheap, lightweight, has no moving parts and it can transfer data much faster than a DVD. Flash memory is bad as it is easy to lose and the metal part of the flash memory may become bent, damaged, or broken