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A Level Computer Science > 4.7 Fundamentals of Computer Organisation and Architecture > Flashcards

4.7 Fundamentals of Computer Organisation and Architecture Flashcards

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1
Q

The Processor (CPU) (2)

A
  • Performs arithmetic, logical, I/O + other instructions passed from the OS
  • 2 areas: ALU and CU
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2
Q

Arithmetic Logic Unit (ALU) (definition)

A

ALU carries out arithmetic operations + logical operations between data

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3
Q

Control Unit (CU) (definition)

A

CU governs operation of hardware, I/O devices and CPU

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4
Q

CPU Capability Measured in (3)

A
  • Ability to process instructions at a given time
  • Max num bits/instructions
  • Relative clock speed
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5
Q

Main Memory (RAM) (6)

A
  • Primary storage - volatile
  • Used for quick and direct access
  • Stores programs + data currently in use
  • Data can only be manipulated if here
    • Virtual memory must be loaded into RAM to be used
  • Inc.: OS, software app, info for CPU
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6
Q

Read Only Memory (ROM) (2)

A
  • Permanent area of storage for programs that have been installed during manufacture of computer
  • Non volatile
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7
Q

Busses (definition)

A

Pass data around different parts of computer

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8
Q

Address Bus (3)

A
  • identify locations in memory
  • Unidirectional
  • CPU → memory
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9
Q

Data Bus (3)

A
  • pass data/program instr. around computer
  • Bidirectional
  • CPU ←→ memory
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10
Q

Control Bus (3)

A
  • used by CPU to communicate with devices contained in computer
  • Bidirectional
  • CPU ←→ memory
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11
Q

Input/Output Controllers (3)

A
  • Pass info: processor ←→ I/O devices
  • May pass error message/deal with interrupts
  • Contain a kernel: passes the info between the 2 areas
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12
Q

The Stored Program Concept

A

Machine code instructions stored in main memory are fetched and executed serially by a processor that performs arithmetic and logical operations

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13
Q

Von Neumann Architecture (3)

A
  • 1 memory location
  • Direct access from memory to ALU
  • (easy access from ALU to I/O)
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14
Q

Advantages of Von Neumann Architecture (1)

A

Can code with complex/changing problems

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15
Q

Uses of Von Neumann Architecture (2)

A
  • General purpose computing systems
  • Access to memory from all parts of system
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16
Q

Harvard Architecture (3)

A
  • 2 memory locations
  • Instr. and have separate buses
  • Can access/load data & inst. simultaneously
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17
Q

Advantages of Harvard Architecture (2)

A
  • reduces bottle necks
  • can have different bus widths (saves £)
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18
Q

Uses of Harvard Architecture (1)

A

Embedded Systems

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19
Q

Registers (definition)

A

Store single item of data within the CPU

20
Q

MAR (definition)

A

Stores address of where to store/retrieve data (address)

21
Q

MBR (definition)

A

Stores data/instructions that have been retrieved/to be stored (data/instructions)

22
Q

CIR (definition)

A

Holds current instruction after decoded (address)

23
Q

PC (definition)

A

Holds count of instruction next to be executed (address)

24
Q

Accumulator (definition)

A

Holds result of ALU calculations/has to be outputted/inputted (data/instructions)

25
Q

Fetch Execute Cycle: Fetch (7)

A
  • PC copied to MAR
  • MAR copied to address bus and sent
  • CU sends signal to read: control bus
  • Data copied from memory to data bus and sent
  • Data copied from data bus to MBR
  • MBR copied to CIR
  • So not overwritten in execution
  • PC incremented by 1
26
Q

Fetch Execute Cycle: Decode (4)

A
  • Instr split: opcode (inst) and operand (data)
  • CU decodes data
  • Opcode sent to CIR
  • Value sent to ACC/ address sent to MAR
27
Q

Fetch Execute Cycle: Execute (3)

A
  • If necessary data is fetched/stored
  • ALU performs calculations
  • Result stored in register/outputted
28
Q

The Processor Instruction Set

A
  • Complete set of all instructions in machine code that can be recognised and executed by a CPU
  • Processor specific
29
Q

Instruction Parts (2)

A
  • Opcode = instruction (+ addressing mode)
  • Operand = data/address
30
Q

Addressing Modes (4)

A
  • Single bit (1/0)
  • Type of operand
  • Immediate: data to be used immediately #2
  • Direct: address being directed to R2
31
Q

Factors Affecting the Performance of a Processor (6)

A
  • Cache
    • Stores frequently used instruction
    • Enables CPU to access repeatedly used data directly, rather than repeatedly requesting from memory
    • Inside CPU so executes faster than RAM (extremely fast)
  • Clock Speed
    • Instruction executed per second
  • Cores
    • Instruction executed simultaneously
    • Single → double = double amount of instruction processed simultaneously
  • RAM
    • Not as much reliance on virtual mem
  • Virtual Memory
    • Not as much reliance on RAM
  • Bus Width
    • Send whole instruction at once
32
Q

Barcode Reader (4)

A
  • Laser shone from device to barcode
  • Light reflected white, absorbed black
  • Reflected laser hits sensor + recorded
  • Converted to binary
33
Q

Digital Camera (5)

A
  • Light enters camera through lens
  • Lens focuses light onto sensor
  • Colour depends on frequency
  • Sensor = grid where each part has colour recorded
  • Data stored in binary in grid like pattern
34
Q

Laser Printer (7)

A
  • Electron beam fired at -ve drum
  • Creates pattern of +ve charges
  • Drum picks up ink on +ve charges
  • Ink rolled onto paper
  • Drum for each colour: magenta, cyan, yellow, black
  • Colours layer
  • Paper rolled through heat press - fuses ink to paper
35
Q

RFID Reader (5)

A
  • Reader transmits data via radio waves
  • Energy activates chip
  • Chip modulates energy
  • Signal transmitted back to reader
  • Info received stored and/or compared to database
36
Q

Secondary Storage (2)

A
  • Where hard disk is not immediately accessible by processor
  • Needed once primary storage is full
37
Q

Hard Disk Drives (4)

A
  • magnetic
  • +ve and -ve charges (1s and 0s)
  • Write: head charges tape accordingly using em charge
  • Read: head attracted/repelled depending on if 1/0
38
Q

Advantages of Hard Disk Drives (3)

A
  • fast read/write
  • large capacity
  • very reliable
39
Q

Disadvantages of Hard Disk Drives (2)

A
  • moving parts (corruptible)
  • expensive
40
Q

Optical Disks (4)

A
  • Pits and peaks in spiral = 1s and 0s
  • Laser pointed at surface and reflected
  • Time for reflection recorded
    • Short = peak = 1
    • Long = pit = 0
41
Q

Advantages of Optical Disks (3)

A
  • small physical size
  • very reliable
  • large storage for BluRay
42
Q

Disadvantages of Optical Disks (3)

A
  • easily scratched
  • can’t be edited after
  • small storage for CD/DVD
43
Q

Solid State Drive (4)

A
  • Flash
  • Non volatile
  • Uses electrical effects to store data
  • No moving parts
44
Q

Advantages of Solid State Drives (4)

A
  • very tough
  • reliable
  • compact
  • fast
45
Q

Disadvantages of Solid State Drives (2)

A
  • data stored in chunks (not good for main memory that needs byte-level access)
  • wears out over time (limited read/write cycle)
46
Q

Interrupts (3)

A
  • purpose is to allow the current instructions to be stopped
  • so an urgent error can be fixed/dealt with
  • before an interrupt is run, all data and registers need to be saved so the process can be executed again after dealing with the interrupt
47
Q

Status Register (3)

A
  • holds information about the result of any logic or arithmetic calculation (e.g. carry bit)
  • used in branch conditions
  • may carry overflows/interrupt information

A Level Computer Science (13 decks)

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