Lecture 1 Chapter 1

Question 1

What are the 4 parts of a computer

Answer 1

CPU RAM IO and BUS

Question 2

What does the ALU do

Answer 2

Carries out basic arithmetic and logical operations

Question 3

What does the CU control unit do

Answer 3

Determines the sequence of operations

Question 4

What are registers

Answer 4

Small memory in the CPU for immediate data and results

Question 5

What does the Program counter PC register hold

Answer 5

The address of the next instruction to be executed

Question 6

What does the Instruction register IR hold

Answer 6

Holds the current instruction data

Question 7

What does the Accumulator AC hold

Answer 7

Partial results of any computation

Question 8

What does the Memory Address register hold MAR

Answer 8

Holds the address of the current instruction or data

Question 9

What does the memory Buffer data register hold MBR

Answer 9

Hold the current data or instruction

Question 10

What does the I/O address register hold? I/O AR

Answer 10

The address of the I/O device

Question 11

What does the I/O buffer register hold
I/O BR

Answer 11

Data from the I/O devices

Question 12

What do the first 4 bits of the Instruction hold

Answer 12

The Opcode (instruction to be performed)

Question 13

What do the last 12 bits of the instruction contain?

Answer 13

The address of the operation

Question 14

What are the two stages of the instruction cycle?

Answer 14

Fetch and Execute

Question 15

What are the three types of Instructions?

Answer 15

CPU arithmetic or logical operation
Communication with memory
Communication with I/O devices

Question 16

What is the process required for a single instruction called?

Answer 16

The instruction cycle

Question 17

What happens to the PC during instruction cycle

Answer 17

It is incremented at each fetch

Question 18

Processor

Answer 18

Controls Computer Operation, preforms data processing functions

Question 19

User -visible

Answer 19

basic type of register, available to all programs, can be referenced by a user/programmers instruction set

Question 20

Control and Status

Answer 20

Basic type of register, used by CPU to control execution of programs

Question 21

MAR

Answer 21

register for processor to exchange data with memory, specifies the next address is memory for next read or write

Question 22

MBR

Answer 22

register containing data to be written to memory, or data from memory

Question 23

IO AR

Answer 23

register with the address of a particular I/O device

Question 24

IO BR

Answer 24

Register for exchange of data between IO and processor

Question 25

Main Memory

Answer 25

Stores data and programs, volitaile, contains a set of locations with addresses, each location contains a bit pattern interpreted as instruction or data

Question 26

IO modules

Answer 26

move data between computer and external environment, contains internal buffers for storing data for sending

Question 27

System BUS

Answer 27

Communication pipeline between components

Question 28

What does a program consist of

Answer 28

Instructions stored in memory to be executed by the processor

Question 29

Why would program execution stop?

Answer 29

If processor turns off, an error occurs, or an instruction to halt is received.

Question 30

What are the four categories of instructions?

Answer 30

CPU-MEM CPU-IO Data Processing Control

Question 31

What is a control instruction?

Answer 31

An instruction that specifies a change to the sequence of execution

Question 32

What is a Data Processing instruction?

Answer 32

The processor will preform an arithmetic or logical operation on data

Question 33

What is a processor - IO instruction?

Answer 33

Data will be transferred between processor and IO module

Question 34

What is a Processor -Memory Instruction?

Answer 34

Data is transferred between the processor and memory

Question 35

What is an Interrupt?

Answer 35

mechanism by which modules interrupt normal sequence of the processor

Question 36

What are the four classes of interrupts?

Answer 36

Program, Timer, IO, Hardware Failure

Question 37

What is a program interrupt?

Answer 37

generated by a condition occurring as a result of instruction execution (arithmetic overflow, division by zero, attempt to execute an illegal machine instruction, reference outside a user's allow memory space)

Question 38

What is a timer interrupt?

Answer 38

generated by timer within processor, allows operating system to perform certain functions on a regular basis

Question 39

What is an I/O interrupt?

Answer 39

generated by I/O controller, to signal normal completion of an operation or variety of error conditions`

Question 40

What is a hardware failure interrupt?

Answer 40

generated by a failure (power/memory parity error)

Question 41

Why are interrupts needed?

Answer 41

Primarily to improve processor utilization

Question 42

What is an interrupt stage?

Answer 42

A stage added to the instruction cycle to accomodate interrupt handling

Question 43

What is the interrupt handler routine?

Answer 43

A process preformed when an interrupt is found during interrupt stage, OS determines nature of interrupt and preforms actions needed.

Question 44

What are the two ways to handle multiple interrupts?

Answer 44

Disable interrupts, priority

Question 45

What are the constraints on computer memory?

Answer 45

1. decreasing cost per bit 2. increasing capacity 3. increasing access time 4. decreasing frequency of access to memory by processor

Question 46

What is the memory hierarchy

Answer 46

Smaller, faster, expensive memories are supplemented by larger, cheaper, slower memories

Question 47

What is locality of reference?

Answer 47

- During program execution, memory references by processor (for both instructions and data) tend to cluster - possible to organize data across hierarchy so that percentage of accesses to each subsequently lower level is much less than that of level above

Question 48

What is a cache?

Answer 48

- high-speed, smaller, extends main memory - stages data movement between main memory and processor registers for performance improvement

Question 49

What are the key elements of cache design?

Answer 49

- cache size - block size - mapping function - replacement algorithm - write policy - number of cache levels

Question 50

What are the three IO operation techniques?

Answer 50

Programmed, interrupt driven and DMA

Question 51

How does programmed IO work?

Answer 51

The processor periodically checks status of I/O module

Question 52

How does Interrupt driven I/O work?

Answer 52

I/O module will send interrupt when ready for service

Question 53

How does DMA driven I/O work

Answer 53

DMA module will use cycle staling to directly communicate with memory