2. Hardware Flashcards
1
Q
What does CPU stand for?
A
Central Processing Unit
2
Q
What does the CPU do?
A
The hardware that executes programs and manages the rest of the hardware.
3
Q
What are the two main parts of the CPU?
A
Control Unit - Sends electrical signals to components to control them
ALU - Carries out all the logic and calculations
4
Q
What does ALU stand for?
A
Arithmetic Logic Unit
5
Q
What things does the CPU need to access?
A
- Main Memory (RAM)
- Storage devices (Hard disk)
- Input/Output Devices
6
Q
How does the CPU access the things it needs to access?
A
A system of Buses (wires).
7
Q
What is measured in Ghz?
A
The amount of instructions that can be carried out per second. (Clock speed)
8
Q
How many calculations per second is 1 Ghz?
A
1 billion
9
Q
What is a multi-core processor?
A
One component where two or more CPUs (processors) or ‘cores’ work together to improve the clock speed.
10
Q
What is cache memory?
A
Memory close to the core processor with very rapid response. It is used to store instructions before they are executed and temporary data.
11
Q
What is architecture?
A
How large the gap between transistors is and how many transistors are on a chip.
12
Q
What is memory?
A
How computers store data and programs.
13
Q
What is RAM?
A
- ‘Main Memory’
- Loads programs and data before running
- Storing generated data before they are stored permanently
- Allows CPU to access data from hard disk
- Volatile -> Loses content when power is turned off
14
Q
What is ROM?
A
- Holds programs that start up the computer (boot up programs) and programs that have information about the hardware
- Non-Volatile -> ‘Remembers’ state
- Cannot easily be overwritten
15
Q
What are the main differences between RAM and ROM?
A
RAM
• Loses its data when computer is switched off
• Temporary storage that is constantly being written to and read from
ROM
• Retains its data even when computer is switched off
• ‘Read only’ and cannot easily be changed by the program or user
16
Q
What does RAM stand for?
A
Random Access Memory
17
Q
What does ROM stand for?
A
Read Only Memory
18
Q
What is virtual memory?
A
When there is not enough space on RAM, an area of the hard disk is used for temporary memory. This is, however, much slower than RAM.
19
Q
What are some examples of magnetic devices?
A
- Tape Drive / Digital Audio Tape
- Hard Disk Drive
- Floppy Disk Drive / Disk
20
Q
How do magnetic devices work?
A
By setting an area of magnetic coated material to NS or EW setting. This can then be scanned by a read/write head.
21
Q
What are some examples of optical devices?
A
- CD - Rom, CD - R, CD - RW
- DVD - Rom, DVD - R/RW/RAM
- Blu-Ray
- HD-DVD
22
Q
How do optical devices work?
A
They are read using light - usually laser light (lighter and darker areas are detected). Commercially, troughs are cut into the disk surface. At home, colour change is used.
23
Q
What are some examples of solid state technology?
A
- Solid State Hard Disc
- Memory Stick (USB)
- Flash Memory (camera type)
24
Q
How does solid state technology work?
A
There are no moving parts (solid state). Data is stored by applying a voltage to a grid of transistors and enabling or disabling current. NAND gates are used.
25
Why are magnetic drives not appropriate for portable devices?
```
Moving Parts
Slower data transfer times
Less robust
Larger in size
Uses more power than a solid state
```
26
What are buses?
The circuits/internal wiring of that connect the processor and main memory.
27
Remember to look at the diagram for how the CPU moves around instructions.
Pg 9 of textbook
28
Describe the fetch-execute cycle.
• Instruction fetched from main memory
• Control unit decodes instruction
• ALU executes instruction
(There may be storage in main memory after this)
29
What is the unit for clock speed?
Gigahertz (GHz)
30
What is clock speed?
The number of cycles per second that a system is capable of.
31
What is latency?
The time taken waiting for components to respond.
32
Summarise the purpose of the CPU.
* Fetching data and instructions from main memory
* Decoding and executing instructions
* Performing calculations
* Managing the movement of instructions and data to and from peripheral devices
33
What factors affect the performance of a computer/CPU?
* Clock speed
* Number of cores
* Cache memory
* Architecture - how large the gaps between transistors are and how many transistors there are
* Speed of other components - can create bottlenecks
34
What does the control unit do?
Sends electrical signals to components to control them.
35
What does the ALU do?
Carries out all the logic and calculations.
36
What is a quad-core processor?
When there are 4 processing units within the CPU.
37
With what factors can different types of memory be compared?
* Access speed
* Price
* Volatility
38
Why does the processor load programs into the main memory before executing them instead of getting them straight from the hard drive?
Access speed from the hard drive is very slow, so the main memory allows the computer to run faster.
39
What is needed if many programs are running at once?
Lots of RAM.
40
Sort these by access speed: Main memory, Cache, Virtual memory, Processor
1) Processor
2) Cache
3) Main memory
4) Virtual memory
41
Give an example of volatile and non-volatile memory.
Volatile: RAM
| Non-volatile: Hard disk
42
What is the bootstrap loader?
* The piece of software that loads the operating system.
| * It's the first program that is loaded into main memory from ROM when a computer is switched on.
43
What is secondary storage?
* Devices such as hard disks and memory sticks which are not the main memory.
* They are long term and non-volatile.
(Basically any storage that is not main memory)
44
What is the need for secondary storage?
To allow files to be stored for a long period of time. Main memory can't do this.
45
Describe how a program is loaded.
* Program is loaded into main memory
* The processor is given the address of the program in main memory
* The processor can run the program instruction by instruction
* Each time the processor fetches an instruction, decodes it, and then runs it
45
What is the fetch-execute cycle?
The cycle that the CPU goes through as it fetches instructions from memory, decodes them and executes them. This repeats.
45
What is the primary memory?
Main memory (RAM)
45
What factors must be considered when picking a type of secondary storage for a specific purpose?
* Capacity
* Access speed
* Portability
* Durability
* Reliability
46
What are some common secondary storage types?
* Optical
* Magnetic
* Solid state
47
What is the reliability of a storage technology?
How long it will last.
48
What is the durability of a storage technology?
How easily it is damaged (e.g. by dropping)
49
Evaluate magnetic memory in terms of cost, capacity, access speed, portability, durability and reliability.
* Cost: Cheap
* Capacity: High
* Speed: Slow
* Portability: Usually not very portable
* Durability: Vulnerable to movement, heat and magnetic fields
* Reliability: Very good
50
Evaluate optical memory in terms of cost, capacity, access speed, portability, durability and reliability.
* Cost: Cheap
* Capacity: Low
* Speed: Very slow
* Portability: Portable
* Durability: Not too durable -> Not good for long term
* Reliability: Good, but degrades over time
51
Evaluate solid state memory in terms of cost, capacity, access speed, portability, durability and reliability.
* Cost: Expensive
* Capacity: Medium
* Speed: Fast
* Portability: Portable (except internal solid state / flash storage)
* Durability: Very durable
* Reliability: Very reliable
52
Aside from portable storage such as USB drives, what can solid state memory be used for?
* As a replacement for a hard disk in notebooks and tablets (internal solid state) or cameras and phones (memory cards) since it is a non-volatile type of RAM.
* It can't be used as a replacement for the main memory since the access speed is too slow.
53
What is the processor?
The component in the computer that fetches, decodes and executes instructions.
54
What is flash memory?
Basically, it is solid state memory, so it has no moving parts. The two terms are used synonymously sometimes.
55
Compare the different types of storage by capacity?
Optical: Low
Solid state / Flash: Medium
Magnetic: High
56
Describe how memory changes are advancing computers.
* Capacity and density are increasing -> Increased number of transistors -> Doubling every 12 to 17 months
* Speed -> Flash memory is replacing magnetic hard disks
* Cost of memory decreasing
57
What is an input device?
Any device that helps to input data into a computer.
58
What is an output device?
Any device that outputs data from the computer to the user.
59
How does a keyboard work?
Pressing a key generates a character code which is sent to the computer.
60
How does a mouse work?
The mouse detects movements using either a ball or a reflected light source under the mouse.
61
What is OMR and how does it work?
* Optical Mark Recognition is used for detecting answers on multiple-choice tests, forms and lottery tickets.
* Works by reflecting light off the boxes, which reflect less light if they are shaded.
62
What is OCR and how does it work?
* Optical Character Recognition is similar to OMR, but is used to convert markings into text
* Works by reflecting light off the markings
63
What is a sip-and-puff switch?
An assistive input device which detects breathing in order to control a computer for a disabled person.
64
Name two types of monitor.
* CRT Monitor - Cathode Ray Tube
| * TFT Monitor - Thin Film Transistor
65
What is a CRT monitor and where is it used?
* Cathode Ray Tube Monitor
* Heavy, old-fashioned monitor that takes up a lot of space
* Used only in places like factories because they are more robust
66
What is a TFT monitor and where is it used?
* Thin Film Transistor Monitor
| * Newer, thinner type of screen which most people have at home on laptops
67
What is LCD technology?
Liquid Crystal Display - an earlier version of TFT screens
68
Name four types of printer.
* Inkjet printer
* Laser printer
* Dot-matrix printer
* Braille printer
69
How does an inkjet printer work and what are the advantages and disadvantages?
* Works by spraying ink onto the page
* Advantages: Good for low cost printing of text
* Disadvantages: Slow, Smudged by highlighter
70
How does a laser printer work and what are the advantages and disadvantages?
* Laser beam is moved along page, creating static charge. Toner powder is attracted to this and is sealed by heat rollers.
* Advantages: Faster, Quieter, Doesn't smudge, Better images
* Disadvantages: Expensive
71
What is a dot-matrix printer and how does it work?
* Printers which existed before inkjet and laser printers
| * Work like a typewriter as a print head has to strike the paper through an ink ribbon to print text
72
What is a Braille printer?
An impact printer that creates raised dots to allow blind people to read.
73
What is an actuator?
A device that performs some sort of action (based on inputs). E.g. A voice sensor might trigger a motor to close some curtains
77
Give some examples of inputs in a supermarket checkout.
* Barcode scanner
* Scales
* Touch-screen
* Keypad
* Chip & pin reader
* Magnetic stripe reader
78
Give some examples of outputs in a supermarket checkout.
* LED display
* Receipt printer
* Speaker
* Touch-screen
79
Give some examples of inputs in an automated home for a disabled person.
* Microphone
* Pressure sensor
* Movement sensor
* Digital camera
* Touch-screen
80
Give some examples of outputs in an automated home for a disabled person.
* Lights
* Motors
* Monitor
* Speakers
* Touch-screen
* Switches
81
Give some examples of inputs for monitoring a patient in hospital.
* Heart rate sensor
* Blood pressure sensor
* Breathing sensor
* Temperature sensor
* Touch-screen
* Buttons
82
Give some examples of outputs for monitoring a patient in hospital.
* Warning lights
* Speakers
* Monitor
* Printer
* Touch-screen
* LED display
83
What is a Boolean expression?
An expression that is either true or false (e.g. X=10)
84
What is a truth table?
A table that shows all the possible combinations of inputs and their logical
output value.
85
What are the main logical operators?
AND, OR, NOT
86
What is a logic diagram?
A diagram of a circuit showing logic gates with inputs and the output these
generate.
87
What is a transistor?
A tiny switch that can be set to on or off.
88
Why do computers use binary?
They contain thousands of transistors which can be set to either on or off.
89
Remember to revise truth tables.
Pg 27 of textbook.
90
What is the circuit symbol for an AND gate?
A D shape.
| See Pg 28 of textbook
91
What is the circuit symbol for an OR gate?
A D shape with a curved left edge.
| See Pg 28 of textbook
92
What is the circuit symbol for a NOT gate?
A triangle with a circle after the point.
| See Pg 28 of textbook
93
How can an AND gate symbol be turned into a NANAD gate symbol?
A small circle is added just after the symbol.
94
What is the best way to complete a table for a complex logic gate, like a NAND gate?
Work through it stage by stag. E.g. Write the results of AND first, and then reverse these to get NAND
