ch4 Flashcards

1
Q

features of the Von Neumann
architecture

A

1- has a central processing unit (CPU or processor)
2- a processor that can access data directly
3- computer memories that could store programs as well as data
4- stored programs made up of instructions that could be executed in sequential order

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2
Q

main components of the processor

A

1- arithmetic logic unit
2- control unit
3- system clock
4- immediate access store

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3
Q

Arithmetic logic unit (ALU)

A

component of a processor that carries out all arithmetic and logical operations

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4
Q

accumulator

A

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

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5
Q

job of control unit

A

Ensures the execution of instructions in the correct sequence. The CU ensures synchronisation of data flow and program instructions throughout the computer.

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6
Q

job of system clock

A

A system clock is used to produce timing signals on the control bus to ensure this vital synchronisation takes place

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7
Q

immediate access store

A

hold data temporirly that the cpu needs to access

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8
Q

register

A

temporary component in the processor that can be general or specific in its use that holds data and instructions as part of the fetch and execute cycle

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9
Q

job of general purpose register

A

holds data that needs to be frequently accessed by the cpu or by the programmer when accessing the cpu directly

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10
Q

job of specific purpose register

A

has a specific function within the cpu and holds the program state

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11
Q

index register

A

used when carrying out index addressing operations

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12
Q

status register

A

used when an instruction needs some sort of arithmetic or logical processing

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13
Q

address bus

A

carries the addresses throughout the computer (unidirectional bus)

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14
Q

data bus

A

carries data from from processor to memory (vise versa) and input/output devices
(bidirectional)

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15
Q

control bus

A

carries signals from control unit to other components of the computer (bidirectional)

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16
Q

four factors that effect the computers overall performance

A

1- width of the bus: the wider the bus the more bits can be transferred each time
2- clock speed: the higher the speed more number of FE cycles is done per second
3- cache memory: the higher the capacity the more instructions can be stored to be accessed b the cpu
4- number of cores: the higher the number the more instructions can be carried out simultaneously

17
Q

fetch and execute cycle

A

the address in the pc is incremented by one and that address is then stored in the mar. mar holds the address of memory location that needs to be fetched. the mdr holds data that is read from or currently written to, the instructions in the mdr are then transferred to the cir to be decoded, the decoded instructions are then executed by the processor

18
Q

what is an interrupt

A

a signal sent from the software or a device to the processor which will temporarily cause it to stop until error is fixed

19
Q

handling interrupt signals

A

interrupt signals are checked at the end or beginning of each
FE cycle, and priority is checked; if priority is higher than current process, the current registers are stored on stack. the location of the interrupt is found. an isr is then used to handle the interrupt signals and when done the cpu is checked once again for interrupt signals until none is found

20
Q

stored program concept

A

data that is stored in the same memory space

21
Q

index register p1

A

stores a value that is added to the index to give a new address

22
Q

status register p1

A

stores flags from the result of arithmetic or logical operation and interrupt flags

23
Q

purpose of cu p1

A

-produces signals to ensure synchronization of data flow throughout the computer
-sends and receives control signals along the control bus
-manages the execution of instruction

24
Q

purpose of interrupt p1

A

sends a signal to get the attention of the processor to fix an error

25
Q

causes of software interrupt

A

array index out of bound
stack overflow
attempt to access invalid memory location

26
Q

immediate addressing

A

the value of operand is only used

27
Q

direct addressing

A

the contents of the address of the operand are used

28
Q

indirect addressing

A

the contents of the contents of the memory location in the operand are used

29
Q

indexed addressing

A

the contents of the memory location found by adding the value in the index register to the address of memory location of the operand

30
Q

relative addressing

A

the memory address of the current memory address added to the operand

31
Q

first/second pass in assembler

A

-remove comment: first pass
-read the assembly line by line: first and second
-generate the object: second
-check the opcode is in the instruction set: first