System Architecture Flashcards
Hardware
any physical component that makes a computer
Software
any program that runs on a computer
Memory (primary storage)
used for holding instructions currently being executed
secondary storage
data that may be needed to perform processing
cpu (central processing unit)
hardware that executes programs and manages the rest of the programs
cpu
control unit
- controls execution of instructions in correct sequence
- decodes instructions
- regulates and controls processor timing using regular pulses from system clock
- sends and recieves signals from other devices in comp
cpu
alu (arithmetic logic unit)
- maths
- logical: and, or, not
- shift: letters can be shifted by a few places
MAR (memory address register)
holds address of data/instruction to be fetched/stored
MDR (memory data address)
holds data/instruction temporarily
PC (program counter)
holds memory address of next instruction
ACC (accumulator)
results of stuff in ALU is temporarily stored
factors affecting CPU perfomance
- clock speed
- cache size
- number of cores
clock speed
number of cycles per second (hertz/gigahertz)
cache memory
- faster memory where frequently used instructions and data can be stored
- more expensive
number of cores
- parallel processing
- more than one instruction can be executed at once
- only faster if computer is designed for multi-cores
embedded systems
small computer built into a piece of equipment built to perform a specific action
* cameras
* ovens
* fridges
* satnavs
random access memory
RAM
- volatile mem that can be written to and read from
- temp storage for programs being executed bc faster access times
virtual memory
- secondary storage as additional primary storage
- allows data in the RAM not being used to be held in hard disk
- slower access time
read only memory
ROM
- non-volatile
- can only be read
- usually has the comps op system
secondary storage
factors to consider
- capacity
- speed
- portability
- durability
- reliability
- cost
secondary storage
magnetic devices
- slow
- low durability
- less portable
- high capacity
- high cost
- reliable
secondary storage
internal solid state
SSD
- expensive
- high capacity
- fast
- not portable
- extremely relaible
- used for laptops
seconday storage
USB memory stick
SSD
- cheap
- normal capacity
- normal speed
- small = portable
- v durable
- v reliable
- personal use
secondary storage
memory card
solid state storage devices
- normal price
- avg capacity
- depends
- v small bc designed for portable devices
- v durable
- v reliable
- in phones and cameras
secondary storage
CD
optical storage device
- 20p/CD
- 640MB capacity
- normal
- portable
- depends - can last 10-25yrs but affected by sunlight
- medium term reliability
- software distribution or backup/archive
secondary storage
DVD
optical storage device
- 24p/DVD
- bigish capacity
- 16MB/s
- portable
- depends
- medium term reliability
- backup, software distribution, storage
secondary storage
blu-ray
optical storage device
- 44p/bluray
- bigger capacity
- 50MB/s
- portable
- depends - lifetime 20-100yrs
- medium term reliability
- storage, backup
