Chap 3 - hardware Flashcards
define CPU
central processing unit
-executes/ processes instructions & data in the comp.
-consist of control unit (CU), arithmetic & logic unit (ALU), memory unit (registers) & buses, cache memory
examples of instructions that can be executed by CPU
-video calls
-instant message
-opening application e. Spotify
difference btw processor & microprocessor
processor - do many tasks
microprocessor - does only 1 task
2 types of computers & what are they
1) Fixed program computers:
-specific functions
-can’t be reprogrammed
eg. calculators
2) Stored program computers: Von- Neumann architecture
-carry out diff tasks/ applications stored in them
characteristics of Von- Neumann architecture
-Must have a processor/s
-has CPU, memory & storage
-Processor must talk directly to Memory ( RAM)
-Memory contains stored program that has instructions & data
-Each instruction is executed line by line
what is stored program
-program stored in RAM which has instructions & data
-instructions are loaded from storage to RAM
-instructions are executed line by line
use of control unit (CU) in CPU
-sends control signals to synchronize execution of instruction & data movement
-uses system clock to produce timing signals on control bus, else the comp will crash
uses of memory unit (registers) in CPU
-made of registers that are used for storing immediate result temporarily during fetch, decode & execute cycle
-PC, MAR, MDR, CIR, ACC
use of arithmetic & logic unit (ALU), in CPU
-carry out arithmetic & logical operations of binary no.
-NOT A REGISTER
define system buses
buses used to transmit data through parallel transmission
-parallel = data not arrived in order, faster than serial
types of system buses & their directions (they’re all parallel transmission)
-address bus - unidirectional = from CPU to RAM - memory address of instructions
-data bus - bidirectional = from CPU to RAM & RAM to CPU
-control bus - bidirectional = sends and received control signals to & from components
types of register & their uses
-program counter (PC) - stores address of next instruction
-memory address register (MAR) - stores address of memory location currently being read form/ written to
-memory data register (MDR) - stores data that is has just been read from memory/ data about to be written to memory
-current instruction register (CIR) - stores current instruction being decoded & executed
-accumulator (ACC) - stores data temporarily while ALU does calculations
which registers belong to which unit in the CPU
-PC = memory
-ACC = ALU
-MAR = memory
-MDR = memory
-CIR = control unit
Fetch, decode & execute process
-CPU fetches data & instructions & stores them in Immediate Access Store (IAS)
-memory address of NEXT instruction is stored in PC from RAM
-address is loaded to MAR which is loaded into address bus
-contents of memory address is loaded from data bus into MDR
-data is loaded in CIR.
-Control Unit decodes instruction using instruction set into opcode & operand
-instructions are sent to ALU which executes it. ACC temporarily holds data while ALU executes them
-PC value is loaded onto MAR & process continues until all instruction are executed
fetch: get data from RAM
decode: decode instruction to be interpreted
execute: CPU passes decoded instructions to components by a set of control signals
How to write correct binary for MAR & MDR
-find binary in address column for MAR
-find binary in contents next to address binary for MDR
factors that affect the performance of a CPU
-clock cycles
-width of system buses
-cache memory
-CPU cores
define cache memory
memory in the CPU that stores frequently used instructions & data that need to be accessed faster
-CPU checks cache before checking RAM
how does clock cycles affect the performance of a CPU
-increasing clock speed, increases CPU speed
-heat processor up = unreliable performance
-not good to overclock CPU beyond its normal design
how does width of system buses affect the performance of a CPU
-increasing bus width, increases CPU speed
how does cache memory affect the performance of a CPU
-increasing cache memory, increases CPU speed
-can store more data that is frequently used
how does CPU cores affect the performance of a CPU
-increasing CPU cores, increases CPU speed
-multi processing = more fetch, decode & execute cycles per second
-1 core has ALU, CU & registers
-CPU needs to communicate with each core = reduce overall performance
define clock cycles
no. of CPU/ fetch, decode & execute cycles in 1 second
-synchronizes diff operations
-each clock cycle send out a clock or timing signal
-based on the system clock
define overclocking
-increasing the clock speed of a comp
-clock speed can be changed by altering settings in Basic input/ output system (BIOS)
-executing instructions outside of comp limits can cause unsynchronized operations = frequent crashing
-leads to lot of overheating = unreliable performance
purpose of primary & secondary storage
primary - volatile, stores data currently used by CPU
secondary - non- volatile, stores data not currently used by CPU
