4. Processor fundamentals

Stages of fetch execute cycle(5)

1. PC holds the address of the next instruction to be fetched 2. The address in PC is copied to MAR 3. The PC is incremented 4. The instruction is copied from address stored in MAR to MDR 5. The instruction from the MDR is copied to CIR

Data Bus (3)

1. carries data between processor and memory 2. bi-directional bus 3. used to exchange data

benefits of HDMI (3)

1. current standard for modern televisions and monitors 2. allows very fast data transfer rate 3. improved security, helps prevent piracy

Control Unit (CU)

1. directs and coordinates other parts of the computer system 2. controls operations of computer system 3. fetches computer instructions 4. decodes computer instructions 5. executes these instruction

Number of Cores (CPU Performance)(3)

1. each core processes one instruction per clock pulse 2. more cores mean that sequence of instructions can be split between them and so more than one instruction is executed per clock pulse 3. more cores decreases the time take to complete task

Benefits of USB port(4)

1. fast data transfer 2. automatic connection 3. industrial standard 4. device may be powered or charged through USB

difference between general purpose and special purpose register (2)

1. general purpose registers holds the temporary data while performing different operations 2. special purpose registers holds the status of a program

HDMI(high-definition multimedia interface)(5)

1. helps to connect more monitors 2. allow to output both audio and visual 3. support high definition signals 4. faster data transfer 5. increases the bandwidth making it possible to supply the necessary data for high quality sound and visual effects

cache memory (CPU performance)(2)

1. improves processor performance, similar to RAM, have a faster access time as there is no need to keep refreshing 2. it stores frequently used instructions and data that needs to be accessed faster

drawbacks of VGA(3)

1. it does not support audio 2. outdated as modern laptops and computers rarely have a vga port 3. easy to bend the pins when making connections

drawbacks of HDMI(2)

1. not a very robust connection 2. limited cable length

clock speed (3)

1. one F-E cycle is run on each pulse 2. the clock speed dictates the number of instructions that can be run per second 3. the faster the clock speed the more instruction can be run per second

benefits of VGA(4)

1. simpler technology 2. only one standard available 3. easy to split signals and connect a number of devices from one source 4. the connection is very secure

register (3)

1. small piece of memory 2. part of the processor 3. temporary storage of data which is about to or has been processed

Status Register

1. the status register deals with eight bits which indicate(or flags) whether something happened when the last instruction was executed.

Disadvantages of USB(3)

1. the transmission is limited to less than 500 megabits 2. the maximum cable length is presently about five metres 3. the older USB standard may not be supported in the near future

Control Bus (2)

1. transmits signals between control unit and other components 2. bi-directional

Address Bus(3)

1. uni-directional bus 2. carries signal related to memory address 3. between processor and memory

logical shift

Bits shifted out of the register are replaced with zeros

Fetch execute in register transfer notations

MAR <-- [PC] PC <-- [PC] + 1 MDR <-- [[MAR]] CIR <-- [MDR]

MDR(Memory Data Register)

Stores data that has just been read from memory

MAR(Memory Address Register)

Stores the memory address where data is to be read from

object code

a computer program after translation into machine code

source code

a computer program before translation into machine code

Assembler

a computer program that translates programming code written in assembly language into machine code. Assemblers can be one pass or two pass

Fetch-Execute Cycle

a cycle in which instructions and data are fetched from memory and then decoded and finally executed

Assembly Language

a low-level chip/machine specific programming language that uses mnemonics

mask

a number that is used with the logical operators AND, OR or XOR to identify remove or set a single bit or group of bits in an address or register

Instructing

a single operation performed by a CPU

USB(Universal Serial Bus)

a type of port connecting devices to a computer

left shift

bits are shifted to the left

right shift

bits are shifted to the right

Arithmetic Logic Unit (ALU)

component in the processor which carries out all arithmetic and logical operations

addressing modes

different methods of using the operand part of a machine code instruction as a memory address

IAS(Immediate access store)

holds all data and programs needed to be accessed by the control unit

Indirect Addressing

mode of addressing in which the contents of the contents of the memory location in the operand are used

Indexed Addressing

mode of addressing in which the contents of the memory location found by adding the contents of the index register (IR) to the address of the memory location in the operand are used

Direct Addressing

mode of addressing in which the contents of the memory location in the operand are used

Relative Addressing

mode of addressing in which the memory address used is the current memory address added to the operand

Immediate Addressing

mode of addressing in which the value of the operand only is used

shift

moving the bits stored in a register a given number of places within the register; there are different types of shift

Cyclic shift

no bits are lost, bits are shifted out of one end of the register are introduced at the other end of the register

system clock

produces timing signals on the control bus to ensure synchronisation takes place.

asynchronous serial data transmission

serial refers to a single wire being used to transmit. bits of data one after the other. Asynchronous refers to a sender using its own clock/timer device rather sharing the same clock/timer with the recipient device.

Opcode

short for operation code, the part of a machine code instruction that identifies the action the CPU will perform

interrupt

signal sent from a device or software to a processor requesting its attention; the processor suspends all operations until the interrupt has been serviced

ISR(Interrupt service routine)

software which handles interrupt request and sends the request to the CPU for processing

PC(Program Counter)

stored the address of the next instruction to be fetched

CIR(Current Instruction Register)

stores the instruction that is currently being executed

ACC(Accumulator)

temporary general purpose register which stores numerical values at any part of a given operation

instruction set

the complete set of machine code instructions used by a CPU

Operand

the part of a machine code instruction that identifies the data to be used by the CPU

Machine Code

the programming language that the CPU uses

Arithmetic shift

the sign of the number is preserved

control

to automatically take reading from a device, then use the data from those readings to adjust

monitor

to automatically take readings from a device

VGA(video graphics array)

type of port connecting devices to a computer

IX(Index Register)

used when carrying out index addressing operations