1
Q
What does the Arithmetic and Logic Unit do?
A
- Handles data processing, performs standard arithmetic operations as well as logic operations and comparisons.
- Completes all the arithmetical and logical operations.
2
Q
What is the Control Unit?
A
- Controls the way the data moves around the CPU - controls buses and flow of data between CPU and other components.
- It executes the instructions given by a program.
- A part of the processor which directs operations inside the CPU.
3
Q
What are registers?
A
- Quick, small stores of data within the CPU.
- Small memory cells that operate at high speeds.
4
Q
What does the Program Counter do?
A
- Holds the memory address of the next instruction.
- Increments by 1 after each fetch stage.
5
Q
Which register does all the calculations?
A
The accumulator
6
Q
What does the MAR do?
A
- Holds the memory address of the data needing to be accessed
- Holds address of a location that is to be read from or written to
7
Q
What does the MDR do?
A
- Holds the data being transferred to or from the memory location by the CPU.
- Temporarily stores the data that has just been read from or the data needs to be written.
8
Q
What does the CIR do?
A
- Contains the current instruction during processing.
- Holds the current instruction divided up into opcode and operand.
9
Q
What is a Bus?
A
- Parallel wires which connect 2 or more components together.
(The width of the bus is the number of parallel wires a bus has. Directly proportional to the number of bits transferred)
10
Q
What is the system bus?
A
The collection of the data bus, address bus, and control bus is called the system bus.
11
Q
What is the data bus?
A
- Bidirectional
- Transports data and instructions between components (to and from memory)
12
Q
What is the control bus?
A
- Bidirectional
- Carries commands from the CPU & status messages from other hardware devices.
13
Q
What does the address bus do?
A
- Unidirectional (only goes from memory to the CPU)
- Transmits the memory address specifying where data is to be sent from or retrieved from.
14
Q
What does adding a wire to the address bus do to the number of addressable locations?
A
- It doubles the amount of addressable locations
15
Q
What does the Bus request indicate?
A
- indicates a device is requesting access to the data bus
16
Q
What does Bus Grant indicate?
A
- Shows that the CPU has granted access to the data bus.
17
Q
What does memory write do?
A
- Data is written into addressed location from the data bus.
18
Q
What does memory read do?
A
- Data from the addressed location to be placed onto the data bus.
19
Q
What does the interrupt request control signal indicate?
A
- Shows that a device is requesting access to the CPU.
20
Q
What is the clock control signal used for?
A
- Used to synchronise all the operations/instructions.
21
Q
What is Assembly Language?
A
Assembly language is a programming language where mnemonics are used to represent instructions.
22
Q
What is opcode?
A
- Part of the instruction code that tells the processor what to do.
23
Q
What is the operand?
A
- Contains the data to be acted on, or the memory location of the data in a register.
24
Q
Describe the Fetch stage.
A
- The address from the PC is copied to the MAR
- Instruction held at that address is copied to the MDR by the data bus, simultaneously the contents of the PC is increased by 1
- The value of the MDR is copied to the CIR
25
Describe the Decode stage.
- The contents of the CIR is split up into opcode and operand.
26
Describe the execute stage.
- The opcode is executed on the data.
27
What is the clock speed?
- The number of cycles completed per second.
28
What is cache memory?
- CPU's onboard memory which is accessed a lot quicker than main memory. Smaller in size but quickest.
29
What is pipe-lining?
- Fetching an instruction whilst the prior one is being decoded and the one before is being executed.
30
What is Von Neumann architecture?
- There is a single shared memory and shared data bus for both data and instructions.
31
What is Harvard architecture?
- Separates the data and instructions into separate memories and data buses for each. The memories can be different sizes making speed a priority.
32
What is contemporary processing?
- Procesing style in which Von Neumann architecture is used for main memory. Cache uses Harvard architecture, divided into instruction cache and data cache.
33
Advantages of Von Neumann
- Cheaper to develop as the CU is easier to design.
| - Programs can be optimised in size.
34
Advantages of Harvard architecture
- Quicker execution as data and instructions fetched in parallel
- Memories can be different sizes, makes more efficient use of space.
35
Disadvantages of Harvard architecture
- More physical space is needed since there are 2 buses. Handling 2 blocks of memory is more complex.
36
What does RISC mean?
- Reduced Instruction Set Computer
37
What does CISC mean?
- Complex Instruction Set Computer
38
What are the properties of RISC?
- Small instruction set
- Each instruction is one line of machine code
- Used in everyday devices.
39
What are the properties of CISC?
- A large instruction set
- Instructions are built into hardware
- Used in embedded systems and microprocessors.
40
What are the benefits of RISC processors?
- Pipe-lining is possible since each instruction takes one clock cycle.
41
What are the benefits of CISC processors?
- Compilers have to do less work
| - They require less RAM since instructions are smaller.
42
What is a graphics processing unit?
- A co-processor made up of lots of independent parallel processors.
43
What are GPU's used for now?
- GPU's are used for image processing and machine learning.
44
What are multi-core systems?
- Systems where there are multiple cores that separate FDE cycles.
45
What are parallel systems?
- Systems where multiple instructions can be completed at any given time, doesn't require multiple cores. it can use threading and pipe-lining instead.
46
Give two types of magnetic storage
- Hard disk drive
- Floppy disk
- Magnetic tape
47
Give three examples of input devices
- Keyboard -Touchpad
- Mouse -Barcode reader
- Microphone
- Webcam
48
Give an example of a device that is both input and output
- Touchscreen
49
What name is given to the areas on a CD's surface which have been burned into grooves by a laser?
- Pits
50
What does CD stand for?
- Compact Disc
51
Give three examples of output devices
- Speaker
- Monitor
- Printer
- Projector
52
Order these from highest storage capacity to lowest:
| DVD, CD, Blu-Ray
Blu-Ray, DVD, CD
53
In a hard disk drive, what is mounted at the end of the actuating arm?
Read/write head (needle)
54
Which storage device has typical capacities in the range 500GB-5TB?
Hard disk drive
55
Give two disadvantages of SSDs
- Higher cost per GB
| - Limited lifespan
56
What does ROM stand for?
- Read only memory
57
Describe the structure in which information is stored in flash memory
- Information is stored in blocks, which are combined to form pages.
58
What is meant by non-volatile?
- Storage medium doesn't lose its information when power is lost.
59
Which two types of logic gates are used in flash storage?
- NOR
| - NAND
60
Give two advantages of SSDs
- Higher transfer speeds
- Lightweight
- No moving parts
61
Is ROM volatile or non-volatile?
- Non-volatile
62
Which form of storage device uses silicon semiconductors to store information?
- Flash
63
Give two disadvantages of CDs
- Easily damaged by scratches
- Relatively low capacities
- Slow transfer speeds
Computer science A Level OCR
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