Computer studies - Chapter 3.1 - 3.11
How many wires are inside a USB?
4 wires
What is the CPU composed of? and what do its components communicate through?
CU, system clock, ALU, registers - tiny, hair-thin chip wires knows an buses
What are the types of registers?
PC, CIR, MAR, MDR, IR OR XR, ACC
What are examples of 2D scanners?
QR codes and fingerprint scanners
What is the cache?
Very fast memory in the CPU
What is a microphone?
a device that accepts sound waves and converts them into digital format using ADC for the computer to process, interpret and store
What makes computerized devices work?
a microprocessor
What is an input device?
a peripheral that is used to enter data into a computer
What is Von Neumann architecture?
a system where the CPU runs programs stored in memory
ACC
accumulator - temporarily stores data being worked on and the results of calculations that were performed by the ALU
What is the operand?
actual data or memory location that will be acted on
What is the ALU responsible for?
all mathematical operations ( - ÷ + ×) and logical operations (and, or..)
What is the CPU?
also called a microprocessor or processor - its a chip that acts like the brain of the computer
What is a barcode scanner?
an input device that reads printed barcodes
What is a trackball?
an input device the controls a cursor on screen
What are ALU and CU?
arthimetic logic unit and control unit
What are some features of an optical mouse?
as mouse moves, the cursor moves on the screen - can be wired (USB) or non wired (bluetooth) - relies on on laser to track movement - options are executed by clicking the left click button but the right click is used to open extra menus
Why does a CPU need a fan?
because it gets very hot while operating
What is a web camera (webcam)?
camera connected to a computer and provides live video over a broadband internet connection, with or without connection - it does not have internal storage
control bus:
carries control signals from the CU to other components of the CPU - carries the clocks pulses - handles interrupts and completed data transfers - mainly unidirectional but can bi bidirectional
data bus:
carries data being transferred from CPU to other components - the larger the data bus the more the data can be transported simultaneously - its bi-directonal
address bus:
carries memory addresses that indicate data storage locations - unidirectional - the larger the address bus the more the data can be transported simultaneously
What are examples of embedded systems?
central heating systems engine management systems in vehicles domestic appliances, such as dishwashers, TVs and digital phones digital watches electronic calculators GPS systems fitness trackers
What is a keyboard?
common input device through which data and instructions may be typed into computer memory
What is an embedded system?
computerized system that uses a microprocessor to perform one or more dedicated functions (they are usually part of a larger system)
What are the characteristics of capacitative touchscreens?
consists of several layers of glass coated with conductive material - as users fingers touch the screen there is a change in electrical field which shows location of contact - can work with multi contact - incompatible with stylus - moderate cost - good visibility in sunlight - high scratch resistance - use with bare hands - used on smartphones - laptops, tablet screens .. - may be affected by magnetic fields
CIR
current instruction register - contains instructions to be decoded and executed
What does secondary storage store?
data and programs permanently while the computer is turnt off
What does primary storage store?
data and programs that are used when the computer is working
What does an instruction set include?
data transfer intructions, arthimetic and logical operations intructions, control of flow intructions
List the three types buses.
data, address and control bus
Explain some features of buses.
each wire in a bus can transmit one bit of data - speed of the bus is measured in MHz - size of a bus is how many bits can be transferred at the same time
What are some characteristics of touchscreens?
easy to use - do not need extra input devices - able to zoom in or out and rotate - can be found in ATMs - not suitable for entering large amounts of data - if screen is damaged, touchscreen will not work
Where are microphones found?
either built in into the computer, or connected as an external device using a USB or bluetooth
What are interactive whiteboards?
electronic virtual whiteboard that connects to a computer, similar to a touchscreen it is both an input and output device - when connected to a computer, the display from computer is projected on the interactive whiteboard
What is clock speed? what happens when the clock speed increases?
frequency (in hertz) of signals sent out - the higher number of instructions that can be performed in the same time interval
Embedded systems have _____ ware.
hard and soft
What is the function of the clock speed or rate in the CPU?
how many instruction cycles the CPU can run in 1 second
disadvantages of embedded systems:
if the embedded computer goes wrong, the equipment stops working they need specialised skills to design an embedded system or to fix it if faulty
IR or XR
index register - it addresses arrays of data, it participates in some arthimetic operation and participates in the calculation of storage addresses
What is a joystick?
input device composed of a handle or stick that is gripped and can be pointed in different directions to control movement objects on screen
What is a digital video camera?
input device that captures a sequence of digital photos - these photos are saved as video file with a sound track
What is a digital camera?
input device that captures photos and stores them on a memoir card or a memory chip
What is a 2D scanner?
input device that is used to convert hard copy images or documents into a digital format that can be stored on a computer
What is a graphics tablet?
input device used to enter images drawn by hand directly on the computer using a pen-like device and a special graphics program
What are embedded systems composed of?
input devices (eg. sensors) - analog to digital and vice versa - actuator (device controlled by the embedded system)
What is the set of basic hardware components of a computer system?
input devices, processing devices, storage devices, output devices
Explain how the von Neumann architecture model works.
input → CU & register ⇄ memory & data, program & data ⇄ ALU & register → output
What is machine code?
instructions written or existing in a form acceptable by a computer.
What are used to convert programming languages?
interpreters and compilers
Is it possible to change the maximum clock speed?
is it is possible to change it in the BIOS (basic input output system)
Why is overclocking not advisable?
it can overheat and destroy the CPU
What is an optical mouse?
it is a pointing input device that a user moves across a flat surface
What is a microprocessor?
it is an advanced integrated circuit (IC) made up of millions of transistors on a single chip
What is a 3D scanner?
it is used to capture a 3-dimensional image of the objects being scanned
Where is the CPU located?
it plugs into place on the computers motherboard, which is the computers main circuit board
What are some examples of input devices?
keyboard mouse joystick scanner web camera microphone
MAR
memory address register - contents of the PC are copied into the location to prepare for the execution to be instructed
MDR
memory data register - register that stores the data retrieved from memory
Define a register.
memory locations that can store a small amount of data
What are the characteristics of resistive touchscreens?
not expensive - made of glass panel covered by metallic paper printed on its underside, under is a layer of conductive material - good resistance to moisture or heat - can work with gloves - easily scratched - poor visibility - doesn't support multitouch - low sensitivity so it requires the user to press harder for a touch to be detected
What is the performance of the CPU affected by?
number of cores, cache size and clock speed
What is the CPU made up of?
one or more processing units called cores, each core has its own CU, ALU and registers
What is a barcode?
pattern of vertical parallel lines of different thicknesses and of numbers that represent data and identify an object
What is a light pen?
pen-like input device that can be connected to a screen - computer determines position of the tip of the pen on the screen by detecting light - are obsolete because of touchscreens
What are the functions of the CPU?
performing complex arithmetic and logical tasks, data processing and operations, controls different parts of the computer, stores immediate data resulting from processing and program instructions
What is a portable digital camera (camcorder)?
permits users to save video tapes, disks, or memory disks to be transferred later onto a computer
Define hardware.
physical devices used to enter, process, store and receive information
What are the 2 types of digital video cameras?
portable (camcorder) and web camera (webcam)
What are some characteristics of a graphics tablet (digitizer)?
portable and light - more accurate drawings - much more expenive - used with certain applications such as CAD (computer-aided design) and editing photographs
RAM is an example of ________ storage.
primary
What are the 2 types of storage?
primary (internal memory or main memory) and secondary (external memory)
PC
program counter - stores address of the next instruction to be executed, it gets incremented after the current instruction is execute
What are programming languages?
programming languages are special languages that software developers use to write instructions for computers to execute
How are programs fetched in the Von Neumann architecture model?
programs are made up of instructions that are fetched, 1 by 1, into the memory, where they are decoded and executed
What are some characteristics of digital cameras?
records images on a sensor called a charge-coupled device (CCD) - uses ADC - memory cards increase the storage capacity of a device - cables or memory card readers can be used to transfer images into the computer - digital cameras allow automatic adjustment of shutter speed, image size, image focus, flash ...
What is an OCR (optical character recognition)?
refers to the technique used to recognize or read text from an image file
What are the three types of touchscreens?
resistive, capacitative and infrared touchscreen
What are the characteristics of 3D scanners?
scans objects along their x, y, and z coordinates - useful in scanning patients internal organs - used in healthcare to build 3D image of a person or organ through thin slices using gamma rays, x-rays and radio frequencies
What does the system lock do?
sends out regular signals to synchronize the operation of different components
What is a computer system?
set of physical devices programmed to accept information from the user to manage, process, and store this information and to produce results
What is a transistor?
small electrical device that controls how current passes in a circuit
What does a keyboard include?
standard keys that use QWERTY (first letters on the keyboard) and sometimes a separate number pad
What are the roles of the CU?
synchronizes the actions of the processor, tells other parts of the processor what to do, decodes instruction, decides which instruction to carry out next and fetches that instruction
What does the cache do?
temporarily stores instructions and data that the processor uses frequently to speed up processing
The higher the amount of cores...
the higher its ability to run several programs in parallel - but it does not double the speed, the speed is wasted on communication between the cores
The more pixels in the CCD...
the higher resolution of the captured picture
What does an input device change?
the input data into binary codes that the computer can store and process
What is computer architecture?
the manner in which a computers hardware is designed to communicate and operate
What is an opcode?
the part of the instruction which specifies the operation to be carried out
Advantages of embedded systems:
their limited number of functions means they are cheaper to design and build. they tend to require less power, some devices run from batteries. they do not need much processing power, they can be built using cheaper, less powerful processors
What do output devices do?
they are used to display results of processed data
What do input devices do?
they are used to enter data
What is a touchpad?
touch sensitive input device found on laptop computers
What are ergonomic keyboards?
types of keyboards that are used to avoid injuries like RSI (repetitive strain injury)
What are the characteristics of infrared touchscreens?
uses glass for screen with a grid of sensors and infrared transmitters - screens detects where is was touched and the beams were interrupted - good durability - multitouch is available - good sunlight visibility - it is affected by moisture and light - expensive
What are the characteristics of a 2D scanner?
uses light reflected from the image or text to create a digital picture, some scanners read pencil marks, some other read characters formed by a special kind of ink
What types of keyboards do mobile devices have?
virtual keyboards - where the typing is done on screen
What are touchscreens?
visual device that acts as both input device and output device
What does the CU do when a program runs?
when a program is executed, the CU manages and controls the execution properly