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Computer Systems (Computer Architecture (Data Bus - Responsible for…
Computer Systems
Computer Architecture
Data Bus - Responsible for transporting the actual physical data, the bits and bytes of information to and from the memory
Control Bus - Carries command and control signals to and from every single connected device.
Address Bus - Responsible for communicating the physical address of computer memory elements/locations that the requesting device wants to access
Program Counter - A register that holds the address of the next instruction to be executes
Control Unit - Co-ordinates and controls all operations carried out by the computer
Fetch-Execute Cycle - The process by which a computer carries out all of its instructions.
ALU - Responsible for arithmetic and logical comparisons
General Purpose Registers - A set of registers which act as a working area, often storing numbers and results of calculations.
Fetch - Decode - Execute
The CPU operates by repeating three operations:
FETCH – causes the next instruction and any data involved to be fetched from main memory
DECODE – decodes the instruction
EXECUTE – carries out the instruction
Repeat…
Storage Devices
Primary storage - RAM and ROM
Secondary storage - Hard Disk Drive (HDD) - Solid State Drive (SSD)
Offline sacondary storage - Compact Disc (CD) or Digital Veratile Disc (DVD) or BluRay - USB Flash Memory - Removable HDD - Magnetic Tape
Magnetic - Mechanical parts move over the disks surface to read and write data magnetically
Optical - Lasers read and write data using light
Hexadecimal
Base 16 which is made up of A,B,C,D,E,F
Denary to Hexidecimal
e.g. 11 is B in hex. 6 is just 6! So 182 denary = B6 hex
Binary
Base 2 number system and is made up of 1s or 0s (on or off)
Binary is the primary language of the computer
Denary
Base 10 number system that uses numbers 1,2,3,4,5,6,7,8,9,
Denary also means decimal
CPU stands for Central Processing Unit
The CPU carries out arithmetic and logical instructions.
Registers are a type of super-fast on-chip memory
