CS1 week 5 flashcards (MARIE, CPU, Memory...)

1
Q

What is the main role of cpu

A

driving force of fetch, decode, execute instructions (cycle)

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2
Q

What are the 2 principle parts of the cpu

A

. The datapath
.The control unit

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3
Q

What does the datapath consist of

A

It consists of the ALU and registers which are connected to each other and to memory by data bus

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4
Q

What are registers

A

specialised forms of memory that has specific data stored inside it

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5
Q

Why are registers fast?

A

They are close in proximity to cpu

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6
Q

What does the control unit do

A

send signals to activate various components
to perform sequenced operations
.ensure instructions are fetched, decoded and executed in correct sequence

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7
Q

How is computer memory ordered

A

A linear array of addressable storage cells

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8
Q

What is a word

A

A storage cell of memory of fixed size

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9
Q

what does word addressable mean

A

cpu identifies specific storage cells (words) to read and write data to and from memory

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10
Q

what does it mean by byte addressable

A

cpu identifies data by bytes -smaller parts (usually half) of a word- eg if a word is 16 bits processor may identify particular 8 bits of memory rather than the word

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11
Q

How many memory locations is 4M X 16 Ram chips

A

4 x 2^20 16 bit memory locations
. M - 2^20
. 16 part of 4Mx 16 tells you no of bits

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12
Q

What are the 2 ways io devices can be connected 2 cpu through interfaces

A

. Memory mapped
.Instruction mapped

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13
Q

What does it mean by memory mapped

A

There is a reserved section of memory for input and output devices through which CPU interacts

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14
Q

What does it mean by instruction mapped

A

CPU has specific instructions for controlling i/o devices

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15
Q

what is a bus

A

An array of wires that simultaneously transmit a single bit along each line

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16
Q

What does an address bus/ line do

A

sends a memory address along the bus from the cpu to the RAM to specify the location in memory where data should be fetched or written to
.uni directional

17
Q

What does the data bus do?

A

. conveys bits from one device to another
sends data to and from memory

18
Q

control bus/ lines

A

determines the direction of data flow and when each device can access the bus

19
Q

What does a clock do

A

synchronises activities of its various components

20
Q

What is the cpu time equation

A

T = seconds / program X no of cycle / instruction X seconds/ cycle

21
Q

What do interrupts do

A

.Alter the normal flow of execution of a program when an event of higher priority occurs
. There are procedures that directs the cpu on actions to take when an interrupt occurs to handle event

22
Q

What is an example of an interrupt event

A

i/ o requests
operational errors (dividing by 0)
invalid instructions

23
Q

What does Accumulator AC register do

A

16 bit register that hold data cpu will process

24
Q

what does the MAR do

A

12 bit register the hold memory address of data referenced

25
Q

what does MBR do

A

16 bits - hold data that has just been read from memory or is about to be written to memory

26
Q

program counter

A

12 bit- holds the address of the next instruction to be executed

27
Q

Instruction register

A

16 bit- holds instruction immediately before its execution

28
Q

Input register (IN)

A

8 bit - holds data read from input device

29
Q

output register

A

8 bit- holds data to be written to output device

30
Q

How are registers connected

A

all of registers connected to each other and memory via a common data bus

31
Q

what does the ISA (intruction set architecture)

A

specifies formate of instructions and operations the machine can perform
. is an interface between software and hardware

32
Q
A