1.2 MEMORY

1.2 MEMORY

ROM
1. READ ONLY MEMORY
  1. ROM is memory that can only be written to once you can only change it when you access bios
    1. BIOS:basic input output system
      1. not part of the CPU
VIRTUAL MEMORY
1. It allows us to run more applications on the system than we have enough physical memory to support.
  1. Virtual memory is a memory management capability of an OS that uses hardware and software to allow a computer to compensate fro physical memory shortages by temporarily transferring data from ran to disk storage
  2. Physical storage is several typesof data storage that exists in most computer systems
RAM
1. RANDOM ACCESS MEMORY
  1. a type of computer memory that can be accessed randomly
  2. that is any byte of memory can be accessed without touching the preceding bytes
    1. RAM stores your data and programs while you are working on them
  3. ram is volatile
CACHE
1. cache is a small part of the memory that's part of the CPU than RAM
  1. The CPU automatically checks cache for instructions before the requesting data from RAM
    1. This saves fetching the instructions and data repeatedly from RAM.
    2. The more cache there is,the more data can be stored closer to the CPU.
      1. cache is graded as level 1 level 2 and level 3
        l1:is usually part of the CPU chip itself and is both the smallest and the fastest to access.its size is often restricted to between 8KB and 64KB
        L2 and L3 caches are bigger than L1.they are extra caches built between the CPU and the RAM. Sometimes L2 is built into the CPU with L1.L2 and L3 caches take slightly longer yo access than l.1. the more l2 and l3 memory available,the faster a computer can run
      2. Not a lot of physical space s allocated for cache. There is more space for RAM'which is usually larger and less expensive
SOLID STATE
1. all-electronic storage device that is an alternative to a hard disk
  1. its including mobile devices,ipods,cameras,laptops and desktops computers.
    1. solid state are faster than hard disks because there is zero latency
      1. ZERO LATENCY- no read/write head to move.
FLASH
1. flash memory is non voliate
  1. memory chip used for storage.
    1. EEPROM-electrically erasable programmable read-only memory.
REGISTER
1. a processor register (CPU register) is one of the small set data holding places that are a part of the computer proccessorn
  1. a register may hold an instruction,a storage address,or any kind of data.
    1. some instructions specify registers as part of the instruction
  2. (such as a bit sequence or individual characters)
role of the power on self-test (POST) in the boot sequence.
1. A power on the self test is the first stop of the boot sequence.
  1. A power on self test checks that basic system devices are present and working properly.
KEYWORDS
1. CPU- Central Processing Unit
2. RAM- Random Access Memory
3. VOLATILE- gets emptied when power is turned off
4. ROM- read only memory
5. FIRMWARE- permanent software programmed into ROM
6. NON VOLATILE- doesn't loose the data when the device has turned off
7. BIOS-basic input/output system contains programs to load the hardware
8. DISK THRASHING-when a computers virtual memory subsystem is in a constant state of paging

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	Erstellt von emily parr vor fast 7 Jahre