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
why does a comp need RAM
store date temporaily
-store data currnetly in use
-so data can be accessed faster
characteristics of primary storage that makes it primary storge
directly accessed by CPU
all sensors
-temp. - temp. change; monitoring temp of paracetamol
-pressure - pressure applied; detect presence of car when pressure is applied
-gas - detect gas level present; monitor pollution, detect leaks in ac
-radiation level - radiation; in nuclear power plants
-humidity - water vapor in air; determine weather for weather stations
-level - ultrasonic to detect change in level of liquid(level of liquid); monitor levels in petrol tank of car
-light - light intensity; street light on & off
-accelerometers - acceleration; to apply airbags in car when rapid deceleration, switch phone btw portrait & landscape
-proximity - detect nearby obj. within distance; face is close to mobile screen
-infrared (passive) - heat radiation given by obj.; security alarm - detect body heat
-infrared (active) - when invisible radiation beam is broken, detect change in infrared radiation; security alarm- intruder breaks beam
-motion - motion; detect people entering for lighting systems
-colorimeter - colour; in chemical reactions
-pH - acidity; making paracetamol
-acoustic - convert detected sound into electrical signals; security alarm- pick up footsteps
-moisture - water levels in; water level in soil to operate pumps
-mag. field - mag. field changes; anti lock braking systems in car
-flow - flow rate of liquid/ gas (amount of liquid); flow of liquid in chemical reaction
-OCR - converts image text into digital data; camera
use of output devices
show information processed by computer
all input devices
-bar code scanner
-QR code scanner
-Digital camera
-keyboard
-microphone
-optical mouse
-touch screen
-2D & 3D scanner
-sensors
all output devices
-actuator
-DLP projector
-LCD projector
-inkjet printer
-Laser printer
-LED screen
-LCD screen
-speaker
-3D printer
types of data storage
-primary = RAM, ROM, cache memory
-internal & external secondary = HDD, SDD, optical drives
-virtual memory
-cloud storage
difference btw primary & secondary storage
primary:
-directly accessed by CPU
-volatile except for ROM
-smaller size
-more expensive
secondary:
-not directly accessed by CPU
-non- volatile
-bigger size
-less expensive
define what volatile
data is lost when device is powered off
what is ROM
-Read only memory
-stores BIOS
what is RAM
-Random access memory
-stores programs & data currently running
-static & dynamic
difference btw static & dynamic RAM
dynamic: DRAM
-made up of capacitors (ABCD)
-needs constant charging
-slower
-uses more power = power needed for a separate circuit to refresh constantly
-less densely packed
-less expensive
static: SRAM
-made up of transistors (STUV)
-no charging needed
-faster
-less power consumption
-more densely packed
-more expensive
difference btw RAM & ROM
RAM:
-temporary memory
-can be used to read & write
-stores programs & data currently run/ processed
ROM:
-permanent memory
-can only be read from
-stores BIOS
relationship btw RAM size & comp speed
larger RAM size = comp operates faster
examples of uses of ROM
-store factory settings
-store set routines
-store ‘start up’ routines
examples of uses of RAM
-playing a video
-playing music
note: magnetic storage = Hard Disk Drive (HDD)
how does HDD work
-the platter rotates whiles the read- write head reads or writes the data
-data is stored in sectors & tracks
-slower data access than RAM
-has latency = time taken for specific block of data to rotate around the read- write head
-data needs to be refreshed
how does Solid State drives (SSD) work
-made up of flash memory chips with NAND/ NOR
-data doesn’t needs to be refreshed
how does optical media work
-the disk has pits & lands which can be detected as binary using a laser
-uses a read & write head like HDD
difference btw HDD & SSD
HDD:
-has movable parts
-movable parts cause friction & heat = slower
-less expensive
-more storage
-moving parts = less durable
SDD:
-has flash memory chips
-NAND chips used to make flash memory are faster
-more expensive
-less storage
-more durable
differences btw CD, DVD & blue ray disk
CD:
-use infrared laser
-least storage = 800MB
-least expensive
-used for storing small audio files & programs
DVD:
-use red laser
-more storage than CD = 4GB
-more expensive than CD
-used for storing SD videos & movies
Blue ray:
-use blue laser
-most storage = 25 GB
-most expensive
-used for storing ultra HD movies & large files
what is virtual memory & how does it work
-oldest (first) data is moved into HDD or SSD instead of RAM when RAM doesn’t have anymore space in it
-HDD is partitioned, data is divided into pages that are sent form RAM to HDD to be temporarily stored until they’re required
benefits & drawbacks of virtual memory
benefits:
-programs larger than physical memory can be executed
-no need to waste memory on data not being used
-reduces need to buy more expensive RAM memory
drawbacks:
-comp runs more slowly - comp needs to swap data btw RAM & HDD/ SSD
-virtual memory stakes up space in HDD that could be used to store files
-system runs away slowly when comp relies on virtual memory heavily
what is could storage, types & how does it work
-when data is stored on remote servers
-physical environment is owned & managed by a company host
public cloud - storage environment where customer & storage provider are diff companies
private cloud - storage provided by a dedicated environment behind the company firewall
hybrid cloud - combination of public & private clouds
-NOT A SECONDARY STORAGE TYPE
benefits & drawbacks of cloud storage
benefits:
-unlimited storage
-can be accessed from anywhere using internet
-more reliable data recovery
-less expertise needed for management
drawbacks:
-needs internet access
-can be hacked
-long term costs add up as subscription is needed
-limited file support
benefits & drawbacks of storing data on cloud than locally
benefits:
-cheaper than buying local hardware
drawbacks:
-limited file support
note: anything that is downloaded & installed is stored on the hard drive = non- volatile, can override data
note: CPU - RAM - HD
what does a 3.5 GHz processor mean
-processor can run 3.5 billion fetch, decode & execute cycles per second
2 ways to join a network
-NIC
-ethernet
define NIC
-network interface card
-needed to allow a device to connect to a network & send & receive data over it
-contain MAC address
-WNIC - wireless; converts wireless signals into a msg that CPU can understand
-land NIC - wired
define MAC address
-identifies the physical address of a device on the network (never changes)
-needed to connect to a network
-Media Access Control
-in hex, 48 bits in 6 groups of 2
-first 6 is manufacturer’s code, last is device’s serial number
define IP address
identifies the global address on the internet
how are IP addresses assigned
-when a device connects to a pvt network, they’re given a pvt IP which is unique in that network but may be the same as another device in another network
-when router connects to internet, it is given a unique IP address by ISP
-all devices connected to the router has the same pub IP as the router but but each have their own diff pvt IP
-ASSIGNED BY ROUTER LOCALLY OR ISP
IPv4
-in denary
-32 bits, 4 octoates, 8 bits per octoate (no matter how small)
-0 to 255 per octoate
2 ^ 32 possible combiantions
IPv6
-in hex
-128 bits, 8 octoates
2 ^ 128 possible combinations
advantages of IPv6 to IPv4
-removes risk of IP address collisions
-has built in authentic checks
-allows for more efficient packet routes
differences btw MAC & IP
MAC:
-unique for device
-can be universal or local
-uses 48 bits
IP:
-may not be unique
-Dynamic IP changes every time device connects to internet; static IP doesn’t change
-can be 32 or 128 bits
differences btw Pvt & pub IP
pvt:
-assigned by router locally
-changes
-managed manually
pub:
-provided by ISP
-fixed
-1 network has 1 public IP for all devices for internet access
static IP
-IP permanently assigned to a device by the ISP; don’t change each time device logs on the network
dynamic IP
-IP assigned temporarily to a device by the ISP; changes every time device logs on the network
-assigned using a Dynamic Host Configuration Protocol (DHCP)
where are static Ip assigned in
-remote servers which host a website
-online database
differences btw static & dynamic IP
dynamic:
-IP can change
-IP is automatically assigned by setting a range
-used for larger networks
-better privacy; Ip changes each time
-has lease time
static:
-IP cannot change
-IP is manually assigned
-used for small networks & servers
-each device is fully traceable
-allows of faster upload & download speed; can access websites directly
no lease time
roles of a router
-finding path to the destination
-forwarding packets
-assigned IP addresses to devices in a network
note: you can have multiple networks on a router
