Section 5: Computer Organisation and architecture

Question 1

control Bus.

• a bus is a set of parallel wires connecting two or more components of a computer.
• Control bus; a bi-directional bus, the purpose of the control bus is to transmit commands timing and specific status information between system components.
• control lines include - memory write = causes data on the data bus to be written into the addressed location, clock = used to synchronize operations.

Answer 1

• a bus is a ___ of ____ wires _______ two or more _______ of a ________.
• _____ __; a __-_____ bus, the purpose of the control bus is to transmit ______ _____ and _____ status information between system components.
• control lines include - ____ write = causes ___ on the data bus to be ____ into the ________ location, clock = used to synchronise operations.

Question 2

Data Bus.

• typically consisting of 8, 16, 32 or 64 separate lines provides a bi-directional path for moving data and instruction.
• the width of the data bus is a key factor in determining overall system performance.

Answer 2

• typically consisting of 8, __, __ or 64 ______ lines provides a __-______ path for ____ data and ________.
• the ____ of the ___ bus is a _____ factor in ________ overall system ________.

Question 3

Address Bus.

• Memory is divided up internally into units called words, a word is fixed size group of digits, each word in memory has its own specific address.
• when the processor wishes to read a word of data from memory, the width of the address bus determines the maximum possible memory capacity of the system.
• E.g. if the address bus consisted of only 8 lines, the the maximum address it could transmit would be 2^8 = 255.

Answer 3

• Memory is ______ up internally into ____ called ____, a word is ____ ___ group of digits, each word in memory has its own _____ _____.
• when the processor wishes to read a word of data from memory, the ____ of the address bus determines the ______ ______ memory capacity of the system.
• E.g. if the address bus consisted of only 8 lines, the the maximum address it could transmit would be 2^8 = 255.

Question 4

Von Neumann Architecture.

• this specifies the basic components of the computer and processor in which a shared bus is used for both data and instruction.
• a program must be resident in the main memory to be executed.
• the instruction and data are both stored in the same place.

Answer 4

• this specifies the basic components of the ______ and _______ in which a _____ bus is used for both ____ and _______.
• a ______ must be resident in the ____ memory to be ______.
• the _______ and ____ are both _____ in the _____ place.

Question 5

Harvard Architecture.

• a computer architecture with physically separate memories for instruction and data.
• used extensively with embedded digital processing.

Answer 5

• a computer architecture with _______ separate _______ for ______ and ___.
• used ________ with _________ ______ processing.

Question 6

Control Unit.

• used to control and coordinates the activities of the CPU, directing the flow of data between the CPU and other devices.
• it accepts the next instruction, breaks down its processing into several sequential steps, manages its execution and stores the resulting data back in memory or a registers.

Answer 6

• used to _____ and ______ the _____ of the CPU, ______ the _____ of _____ between the ____ and other ______.
• it _____ the ____ ______, _____ down its __________ into _____ ________ steps, manages its execution and ______ the _______ data back in _______ or a _____.

Question 7

Arithmetic Logic Unit (ALU).

• this performs arithmetic and logic operations on the data.
• it can perform instructions such; add, subtract, multiply or divide.
• this operation can be done on fixed or floating point numbers.
  it can perform shift operations, Boolean logic operation, compare two values and logical gates such as AND, OR, NOT and XOR.

Answer 7

• this performs _____ and _____ operations on the ___.
• it can perform instructions such; ____, subtract, _____ or ____.
• this ______ can be done on _____ or _____ ____ ______.
  it can ______ _____ operations, ______ logic _______, ______ two ___ and logical _____ such as AND, ___, NOT and ___.

Question 8

The System Clock.

• this generates a series of signals, switching between 0 and 1, billions of times per second.
• this synchronises the CPU operations.

Answer 8

• this ______ a _____ of _____, ______ between _ and _, _______ of times per _____.
• this _________ the ____ operations.

Question 9

General Purpose Registers.

• there are typically up to 16 general purpose registers in the CPU.
• all the arithmetic, logical or shift operations take place in registers.
• an ACCUMULATOR is another general purpose register, used when there is just a single register in which to store the result of each calculation.

Answer 9

• there are ______ up to __ _____ purpose ______ in the ___.
• all the _______, _____ or ______ operations take place in _____.
• an ACCUMULATOR is another general purpose register, used when there is _____ a ____ register in which to ____ the ____ of each _______.

Question 10

Dedicated Registers: Program Counter.

• hold the address of the next instruction to be executed.
• or it can hold the address to jump to if the current instruction is a branch or jump instruction.

Answer 10

• hold the ______ of the _____ ______ to be ______.

- or it can ____ the _______ to _____ to if the current instruction is a _____ or ______ instruction.

Question 11

General Purpose Registers: Current Instruction Register.

• this only holds the current instruction being executed.

Answer 11

• this only ____ the ______ ______ being ______.

Question 12

General Purpose Registers: Memory Address Register.

• holds the address of the memory location from which data or instruction is to be fetched or to which data is to be written to.

Answer 12

• holds the _______ of the ______ _____ from which ____ or ________ is to be ______ or to which ___ is to be ______ to.

Question 13

General Purpose Registers: Memory Buffer Register.

• used to temporarily store the data read or written to memory.
• it is also sometimes known as the memory data register.

Answer 13

• used to _______ _____ the _____ _____ or _____ to ______.

- it is also sometimes known as the _______ _____ register.

Question 14

The Fetch-Execute Cycle: Fetch phase.

1. the address of the next instruction is copied from the program counter to the memory address register, the address is sent via the address bus to main memory.
2. the instruction held at that address is returned along the data bus to the memory buffer register, simultaneously the content of the program counter is incremented so that it holds the address of the next instruction.
3. the content of the memory buffer register is copied to the current instruction register.

Answer 14

1. the ______ of the next ________ is _____ from the ______ ______ to the ______ _______ ______, the ______ is sent via the ______ bus to ______ ______.
2. the ________ held at that _______ is ______ along the ____ ___ to the _____ _____ register, __________ the _______ of the _______ ______ is ________ so that it holds the ________ of the ____ ________.
3. the ______ of the _______ _____ ______ is ______ to the ______ _______ register.

Question 15

The Fetch-Execute Cycle: Decode phase.

1. the instruction held in the current instruction register is decoded. The instruction is split into opcode and operand and the opcode is used to determine the type of instruction and what hardware to use to execute it.

Answer 15

1. the _______ held in the ________ ________ ______ is decoded. The instruction is ___ into ______ and ______ and the _____ is used to _______ the _____ of _______ and what ______ to use to _____ it.

Question 16

Opcode and Operand.

• Opcode - this consists of binary digits representing the basic operation such as add or load, and a 2-digit code representing the addressing mode.
• Operand - depending on the type of addressing (immediate or direct), the operand could take the actual value to be used in the operation or the memory address of the value to be used for an operation.

Answer 16

• _____ - this _____ of _____ digits _________ the basic _______ such as ___ or ____, and a _-___ code representing the _______ ____.
• _____ - ______ on the type of ________ (______ or ______), the _______ could take the _____ value to be used in the operation or the _______ _______ of the value to be used for an operation.

Question 17

The Fetch-Execute Cycle: Execute phase.

1. the instruction is executed, using the ALU is necessary, and results are stored in the accumulator, general purpose register or maim memory.

Answer 17

1. the _________ is executed, using the ___ is necessary, and _____ are stored in the _______, _____ purpose ______ or ______ ______.

Question 18

Factors Affecting Processor Performance: Number of Cores used.

• in a traditional computer, von Neumann, instructions are exited one at a time in a serial manner.
• a CPU can have multiple cores, which in theory allow the CPU to process different instructions at the same time with its own fetch-execute cycle.
• however, having more cores does not always mean it can improve in performance, as other factor can still affect the processor.

Answer 18

• in a traditional computer, von _______, instructions are _____ ___ at a _____ in a _____ manner.
• a CPU can have _______ ____, which in theory allow the CPU to process ______ _______ at the same time with its own ____-_____ cycle.
• however, having more cores does ___ ______ mean it can ______ in _______, as other factor can still affect the ________.

Question 19

Factors Affecting Processor Performance: the amount and type of cache memory.

• cache is a very small or expensive, very fast memory inside or very close the CPU.
• levels of cache; level 1 - extremely fast but small (2 - 64KB) \/\ level 2 - fairly fast and medium-sized (256KB - 2MB) \/\ some CPU have level 3 cache.

Answer 19

• cache is a very ______ or _________, very ____ memory ______ or very ____ the CPU.
• levels of cache; level 1 - _______ _____ but _____ (2 - 64KB) \/\ level 2 - __ __ and ____-___ (256KB - 2MB) \/\ some ___ have level 3 cache.

Question 20

Factors Affecting Processor Performance: Clock Speed.

• one clock cycle per second = 1Hz, measured in (GHz) so 1 billion cycles per second.
• a typical PC has clock speed of 2-4GHz.
• the greater the clock speed the faster instructions will be executed.

Answer 20

• one clock cycle per second = ___, measured in (___) so 1 _____ _____ per _____.
• a typical PC has _____ _____ of - ____.
• the ______ the clock speed the _____ ______ will be _____.

Question 21

Format of a machine code.

Answer 21

• the instruction is split in two parts the opcode and the operand.
• the opcode contains the basic machine operation and the addressing mode.
• the operand contains the actual value to be used or the address location in memory where it can be found, depending on the addressing mode.

Question 22

Addressing mode.

Answer 22

• a 2-digit code.
• immediate addressing; the operand is the actual value to be used.
• direct addressing; the operand holds the memory address of the value to be used.

Question 23

Assembly language.

Answer 23

• a way of programing a computer with mnemonics that can be easier to understand that just machine code.
• example; machine code (0100 1100) == assembly code (LDA #12), easier to understand over 1’s and 0’s.
• the (#) symbol represent immediate addressing, meaning that the value 12 is used.

Question 24

Assembly Language: Codes.

Answer 24

• LDR Rd, ; load the value stored in the memory location specified by into register d.
• STR Rd, ; store the value that is in register d to the memory location specified by the .
• ADD/SUB Rd, Rn, ; add or subtract the value specified by the to the value in register n and store the result in register d.
• CMP Rn, ; compare the value stored in register n with the value specified by the .

Question 25

Assembly Language: Logical Bitwise operators.

Answer 25

• AND/ORR/EOR Rd, Rn ; perform a bitwise logical AND/OR/XOR operation between the value in register n and the value specified and store the result in register d.
• LSL/LSR Rd, Rn, ; logically shift left or right, the value stored in register n by the number of bits specified by the and store the result in register d.

Question 26

Barcode reader: Pen type reader.

• a light sources and a photo diode are placed right next to each other in the tip of the pen.
• to read the bar code, the tip is dragged across all the bars at an even speed.
• the photo diode measures the intensity of the light reflected, this then generates a wavelength.
• the simplest encoding translates the areas of light and dark as 1’s and 0’s.
• most durable type of bar code scanner, can be sealed against dust, dirt and other stuff, suitable for use with portable computers.

Answer 26

• a ____ sources and a _____ _____ are _____ _____ _____ to each other in the ___ of the ___.
• to read the bar code, the tip is ______ _____ ___ the _____ at an _____ _____.
• the _____ _____ ______ the _____ of the light ______, this then ______ a _______.
• the simplest _______ ______ the areas of _____ and _____ as 1’s and 0’s.
• most _______ type of bar code scanner, can be ______ against _____, _____ and other stuff, suitable for use with portable computers.

Question 27

Barcode reader: Laser scanner.

• work in the same way as a pen scanner, except they use a laser as the light source.
• the laser reflect off a moving mirror allowing the barcode to be read from different angles.
• used in the in-counter units in supermarkets.

Answer 27

• work in the _____ ___ as a ___ ______, except they use a _____ as the _____ source.
• the laser _____ off a ______ _____ allowing the ______ to be _____ from ______ _____.
• used in the _______ units in _________.

Question 28

Barcode reader: Charged-Coupled Device reader.

• use an array of hundreds of tiny light sensors lined up in a row at the head of the reader.
• each sensor measures the intensity of the light immediately in front of it.
• a voltage pattern identical to the pattern of the barcode is generated by sequentially measuring the voltage of each sensor in the row.

Answer 28

• use an ____ of ______ of ____ _____ ______ lined up in a ___ at the ____ of the reader.
• each sensor ______ the ______ of the _____ ______ in front of it.
• a _____ ______ ______ to the pattern of the barcode is generated by _________ measuring the ______ of each ______ in the row.

Question 29

Barcode reader: Camara based reader.

• uses a camera and image processing techniques to decode a 1D or 2D barcode.
• an imaging scanner can read a barcode on any surface, printed or onscreen, and can read a barcode that is damaged or poorly printed.
• used in age verification by scanning an individual’s driving licence, couponing, event ticketing.

Answer 29

• uses a _____ and _____ _______ techniques to decode a 1D or 2D barcode.
• an imaging scanner can ___ a barcode on ____ ______, _____ or ______, and can read a barcode that is _______ or ______ ______.
• used in ___ _________ by _______ an ________ driving licence, couponing, ______ ______.

Question 30

Digital Camera.

• uses a charged-couple device sensor comprising millions of tiny light sensors arranged in a grid.
• when the shutter opens, light enters the camera and projects an image onto the sensor at the back of the lens.
• like a CCD barcode scanner, each sensor measures the intensity of each pixel and turns light into electricity and stores the amount of charge as binary data.
• to record colour the sensors are often placed under a mosaic of red, green and blue filters, used to separate the different colour wavelengths.
• the processor can then approximate binary values of the three RGB channels of each pixel based on the values of neighbouring pixels, it then stored in the camera’s memory card.

Answer 30

• uses a _____-_____ _____ ______ comprising _______ of ___ _____ _____ arranged in a ____.
• when the shutter opens, ____ ______ the camera and ______ an image onto the ______ at the back of the lens.
• like a CCD barcode scanner, each sensor ______ the ______ of each ____ and turns ____ into ________ and stores the ______ of ______ as ______ ____.
• to record ______ the ______ are often placed under a _____ of ___, _____ and ______ filters, used to separate the ______ colour ________.
• the processor can then ________ ______ _____ of the three RGB channels of each ___ _____ on the values of _________ pixels, it then stored in the _______ _______ card.

Question 31

Radio Frequency Identification.

• an RFID tag can be read without line of sight and from uptown 300 metres away.
• it consisted of a small microchip transponder and an antenna.
• the antenna must be quite large for it to be able to communicate with a base unit.

Answer 31

• an RFID tag can be ___ _____ line of _____ and from up to _____ _____ away.
• it consisted of a small ________ _______ and an ______.
• the _______ must be _____ _____ for it to be able to _________ with a ____ unit.

Question 32

Passive and Active tags.

• passive tags; they are more cheaper as they do not have a battery, meaning they relay on the radio wave emitted by the reader up to a metre away, to provide enough electromagnetic power to the card. once energised, the transponder inside the RFID tag can send its data to the reader. mostly used in groceries, music CDs, Oyster card.
• active tags; are physically larger as they contain a battery, this allows the tag to actively transmits a signal for readers to pick up. these are used to track things likely to be read from further away. Such as a car passing a motorway toll booth.

Answer 32

• passive tags; they are more ______ as they do not have a _______, meaning they ____ on the ____ wave emitted by the reader up to a _____ away, to provide enough ___________ power to the card. once _______, the transponder inside the RFID tag can ____ its ____ to the _____. mostly used in _______, _____ CDs, _____ card.
• active tags; are ________ ______ as they ______ a _______, this allows the tag to ______ ______ a signal for ______ to pick up. these are used to ____ things likely to be _____ from _______ _____. Such as a __ passing a ______ toll ______.

Question 33

Laser Printer.

• the printer generates a bitmap image of the printed page and using a laser unit and mirror, it draws a negative reverse image onto a negatively charged drum.
• the laser light cause the affect areas of the drum to lose their charge.
• the drum then rotates past a toner hopper to attract charged toner practices onto areas which have not been affected, (toner a powered ink).
• the particles are transferred onto a sheet of paper and then bonded onto it using pressure and heat.

Answer 33

• the printer _______ a _______ _____ of the ______ ____ and using a ______ unit and ______, it draws a ______ _____ image onto a ______ charged _____.
• the ______ light cause the _____ areas of the _____ to _____ their ______.
• the _____ then _____ past a _____ ______ to _____ ______ toner ______ onto _____ which have __ ____ affected, (toner a powered ink).
• the _____ are _____ onto a _____ of _____ and then ____ onto it using _____ and ___.

Question 34

Hard Disk.

• uses a rigid platters coated with magnetic material.
• Iron particles on the disk are polarized to become either a north or south state, representing 1 and 0.
• the disk is divided into tracks in concentric circles.
• the disk spins very quickly at speeds of up to 10,000RPM.
• a drive head moves across the platters, it does not actually touch the platter but floats above it, is used to write or read data from the disk.
• less portable but huge storage capacity.

Answer 34

• uses a ____ _____ _____ with _____ ____.
• Iron particles on the disk are _______ to _____ either a _____ or _____ state, _______ 1 and 0.
• the _____ is ______ into ______ in _______ _____.
• the ____ ____ very ______ at _____ of up to _________.
• a _____ head _____ _____ the ______, it does ____ _____ ____ the _____ but ____ above it, is ____ to _____ or _____ data from the ____.
• less ____ but ___ storage _____.

Question 35

Optical Disk.

• an optical disk works by using a high powered laser to ‘burn’ sections of its surface, making it less reflective.
• a laser at a lower power is used to read the disk by shining light onto the surface and a sensor is used to measure the amount of light that is reflected back.
• pits and lands, this is referred to the areas of the disk that have been burned (pits) and the non-burned area (lands).

Answer 35

• an optical disk works by using a ______ ______ ______ to ‘____’ sections of its ______, _____ it ____ _______.
• a ______ at a ______ power is used to ______ the ______ by ______ ______ onto the _____ and a sensor is used to _______ the _______ of ______ that is ______ back.
• _____ and ______, this is _____ to the ______ of the _____ that have _____ ______ (____) and the non-burned area (_____).

Question 36

Solid-State Disk.

• uses an array of chips arranged on a board, put in the standard size ‘housing’ so that they fir into existing computers.
• SSD comprises millions of NAND flash memory cells.
• has a controller that manages pages and block of memory, each cell works by delivering a current along the bit and word lines to activate the flow of electrons from the source to the drain.
• the current in the word line is strong enough to force a few of electrons across an insulated oxide layer into a floating gate.
• the state of the NAND cell is determined by measuring the charge in the floating gate.

Answer 36

• uses an ____ of _____ arranged on a _____, put in the ______ size ‘_____’ so that they fit into ______ computers.
• SSD comprises ______ of _____ _____ memory ____.
• has a ______ that manages _____ and _____ of ______, each cell works by _______ a ______ along the bit and word lines to ______ the _____ of _____ from the _____ to the ____.
• the _____ in the _____ line is _____ enough to _____ a ____ of _______ across an _______ _____ layer into a ______ gate.
• the state of the _____ cell is _______ by _______ the _______ in the _____ ____.