4.7 Fundamentals of Computer Organisation and Architecture Flashcards
1
Q
The Processor (CPU) (2)
A
- Performs arithmetic, logical, I/O + other instructions passed from the OS
- 2 areas: ALU and CU
2
Q
Arithmetic Logic Unit (ALU) (definition)
A
ALU carries out arithmetic operations + logical operations between data
3
Q
Control Unit (CU) (definition)
A
CU governs operation of hardware, I/O devices and CPU
4
Q
CPU Capability Measured in (3)
A
- Ability to process instructions at a given time
- Max num bits/instructions
- Relative clock speed
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
6
Q
Read Only Memory (ROM) (2)
A
- Permanent area of storage for programs that have been installed during manufacture of computer
- Non volatile
7
Q
Busses (definition)
A
Pass data around different parts of computer
8
Q
Address Bus (3)
A
- identify locations in memory
- Unidirectional
- CPU → memory
9
Q
Data Bus (3)
A
- pass data/program instr. around computer
- Bidirectional
- CPU ←→ memory
10
Q
Control Bus (3)
A
- used by CPU to communicate with devices contained in computer
- Bidirectional
- CPU ←→ memory
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
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
13
Q
Von Neumann Architecture (3)
A
- 1 memory location
- Direct access from memory to ALU
- (easy access from ALU to I/O)
14
Q
Advantages of Von Neumann Architecture (1)
A
Can code with complex/changing problems
15
Q
Uses of Von Neumann Architecture (2)
A
- General purpose computing systems
- Access to memory from all parts of system
16
Q
Harvard Architecture (3)
A
- 2 memory locations
- Instr. and have separate buses
- Can access/load data & inst. simultaneously
17
Q
Advantages of Harvard Architecture (2)
A
- reduces bottle necks
- can have different bus widths (saves £)
18
Q
Uses of Harvard Architecture (1)
A
Embedded Systems
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
Fetch Execute Cycle: Fetch (7)
- 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
Fetch Execute Cycle: Decode (4)
- Instr split: opcode (inst) and operand (data)
- CU decodes data
- Opcode sent to CIR
- Value sent to ACC/ address sent to MAR
27
Fetch Execute Cycle: Execute (3)
- If necessary data is fetched/stored
- ALU performs calculations
- Result stored in register/outputted
28
The Processor Instruction Set
- Complete set of all instructions in machine code that can be recognised and executed by a CPU
- Processor specific
29
Instruction Parts (2)
- Opcode = instruction (+ addressing mode)
- Operand = data/address
30
Addressing Modes (4)
- Single bit (1/0)
- Type of operand
- Immediate: data to be used immediately #2
- Direct: address being directed to R2
31
Factors Affecting the Performance of a Processor (6)
- 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
Barcode Reader (4)
- Laser shone from device to barcode
- Light reflected white, absorbed black
- Reflected laser hits sensor + recorded
- Converted to binary
33
Digital Camera (5)
- 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
Laser Printer (7)
- 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
RFID Reader (5)
- 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
Secondary Storage (2)
- Where hard disk is not immediately accessible by processor
- Needed once primary storage is full
37
Hard Disk Drives (4)
- 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
Advantages of Hard Disk Drives (3)
- fast read/write
- large capacity
- very reliable
39
Disadvantages of Hard Disk Drives (2)
- moving parts (corruptible)
- expensive
40
Optical Disks (4)
- 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
Advantages of Optical Disks (3)
- small physical size
- very reliable
- large storage for BluRay
42
Disadvantages of Optical Disks (3)
- easily scratched
- can't be edited after
- small storage for CD/DVD
43
Solid State Drive (4)
- Flash
- Non volatile
- Uses electrical effects to store data
- No moving parts
44
Advantages of Solid State Drives (4)
- very tough
- reliable
- compact
- fast
45
Disadvantages of Solid State Drives (2)
- data stored in chunks (not good for main memory that needs byte-level access)
- wears out over time (limited read/write cycle)
46
Interrupts (3)
- 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
Status Register (3)
- holds information about the result of any logic or arithmetic calculation (e.g. carry bit)
- used in branch conditions
- may carry overflows/interrupt information
