computer architecture Flashcards
CPU
central processing unit
- interprets and executes programming instructions
ALU
Arithmetic Logic Unit
- does all arithmetic and logical operations
- math
- core
- dual core - two simultaneous operations
CU
control unit
- loading and decoding of instructions
- directs data flow and operation of the ALU
CPU registors
- small circuits in which intermmediate values from the calculations from ALU are stored
- stores instructions from CPU
- MDR, MAR, Accumulator, PC
Accumulator
results of the currently running instructions
PC
program counter
- address of the next needed instruction
MAR
memory address register
- address bus
- stores memory address
- contains RAM address of the next instruction
MDR
memory data register
- data bus
- contains data that will be written to RAM or was read from RAM
RAM
random access memory
- volatile - loses data after power’s lost
- contains data and instructions that computer has loaded ever since booting up
ROM
read only memory
- non volatile
- has the basic input output system that lets the computer know how to find the operating system to boot it after power’s restored
- data couldnt be changed before but now can be through flash upgrades
diff b/w RAM and ROM
RAM : volatile, gigabytes, has all the data and instructions since computer was booted up
ROM : non-volatile, kilobytes, basic input output system
CIR
current instruction register
BUS
wires that connect two components of a computer system
types of busses
- control bus
- data bus
- address bus
cache
fastest way to access data
ONLY from FREQUENTLY accessed sites
CPU only goes to cache instead of RAM
3 levels of cache
L1 - Smallest, Fastest, in CPU
L2 - Medium, Fast, outside processor chip
L3 - Largest, Slowest, in motherboard
machine instruction cycle
fetch - decode - execute - store
explain cycle
instruction fetched from main memory, instructions decoded into commands in CU, commands executed in ALU, results stored in main memory
detailed cycle
address stored in PC, goes to MAR, back to register.
from there, data for that address stored in MDR, goes to CIR.
Control bus takes it to CU, address bus takes to MAR with instruction which reads data for that instruction
Data stored in mDR, goes to accumulator,
Next adress, cycle repeats, new data gone to accumulator
both data go to ALU to be calculated
Accumulator has the new value
cycle repeats
detailed cycle
PC (address) - MAR (address) - address - MDR (instruction) - CIR (instruction) - CU (instruction) - MAR (instruction) - instruction - MDR (data) - ACC (data) - ALU - MDR
persistent memory and its need
maintains data after power outage,
- keeps files for later use
- prevent data loss
Solid State Drive (SSD)
flash based memory thats faster than a hard disk
- USB
- hard drives
- sim card
OPERATING SYSTEM
OS
software that supports the computer’s basic functions
GUI
graphic user interface
- windows, menu, icons to manage user’s interaction with system
CLI
Command line interface
text based user interface to run programs, manage files and interact with the computer
memory management
keeping track of storage devices
- which application has access to which area of memory
- each location in memory can be read, modified and written to by OS
peripheral management
- keyboard, mouse, monitor, and printers controlled through device driver in peripheral management
multitasking
multiple tasks processed in single resource
multiprogramming
multiple programs run together
security
prevents unauthorised access
- user name, passcodes
application software
computer software package that performs a specific task directly
- spreadsheets, CAD (computer aided design), Web browser
features of application software
toolbars, menus, dialogue boxes, GUI
