Lecture 3

Question 1

What is the instruction format

Answer 1

The instruction format is the size and arrangment of components

Question 2

What are the two major components

Answer 2

The function code also called opcode. This specifies the function or the operation performed.

The operand address which specify the locations of the operand

Question 3

What is the basic instruction format of Memory-Reference , Register and Input and outupt instructions

Answer 3

MR = OPcode = 000 ~ 110

RR = 111, I = 0

IO = 111, I = 1

Question 4

What is the operation code field of an instruction

Answer 4

This is a groput of bits that define various processor operations such as add, subtract, complement and shift.

Question 5

What is the address format

Answer 5

This is the part of the instruction format that deals with specifying the address of operands.

Question 6

What are the main methods

Answer 6

3-address machines;
2-address machines;
1-address machines;
0-address machines.

Question 7

What is the instruction cycle

Answer 7

The instruction cycle (also known as the fetch–decode–execute cycle, or simply the fetch-execute cycle) is the cycle that the central processing unit (CPU) follows from boot-up until the computer has shut down in order to process instructions.

Question 8

What is the instruction cycle

Answer 8

Instruction Cycle
Decode Instruction
Read EA from memeory
Execute Instruction

Question 9

What are the registers involved in each instruction cycle

Answer 9

Memory address registers (MAR): It is connected to System Bus address lines. It specifies the address of a read or write operation in memory.

Memory Buffer Register (MBR): Also called Memory Data Register (MDR). It is connected to the system bus Data Lines. It holds the memory value to be stored, or the last value read from the memory.

Program Counter (PC): Holds the address of the next instruction to be fetched.

Instruction Register (IR): Holds the last instruction fetched

Question 10

A computer consists of 5 functionally independent main parts

Answer 10

Input
Output
Memory
Arithmetic and Logic Unit
Control Unit

Question 11

What are the three parts in a CPU

Answer 11

an Arithmetic and Logic Unit (ALU), a Control Unit (CU), and a set of registers

Question 12

What are logic operations

Answer 12

Logic Operations: Logic operations include NOT, AND, OR, NAND, NOR, XOR.

These operations treat the input data as bit patterns and the result of the operation is also a bit pattern.

Question 13

What are shift operation

Answer 13

Shift operations include logical shift and arithmetic shift operations

Question 14

What type of opeartions do the ALU perform

Answer 14

Logic
Shift
Arithmetic operations

Question 15

What are registers

Answer 15

Registers are fast stand-alone storage locations that hold data temporarily

Question 16

Mention some types of registers

Answer 16

Data Registers:
Instruction Registers:
Program Counter

Question 17

What is the control unit for

Answer 17

The control unit controls the operation of each subsystem.

Question 18

What is the internal memory

Answer 18

A small, but extremely quick memory. It is used for any internal computations that need to be done fast without the added overhead of writing to external memory.

Question 19

What is the data buffer for

Answer 19

This buffer is a bi-directional device that holds outgoing data until the memory bus is ready for it or incoming data until the CPU is ready for it.

Question 20

What is the address latch

Answer 20

This group of latches maintain the address that the processor wihses to exhcange data with on the memory bus.

Question 21

What is the I/O ports

Answer 21

These ports represent the device interfaces that have been incorporated into the processor’s hardware.

Question 22

What are configuration registers

Answer 22

These registers contain the flags that represent the current configuration of the processor.

Question 23

What are functions of the processors

Answer 23

i To control the use of main storage to store data and instructions
ii. To control the sequence of operations
iii. To give commands to all parts of the computer system
iv. To carry out processing

Question 24

Describe the two division of the memory stystem

Answer 24

Primary memory: - Is the one exclusively associated with the processor and operates at the electronics speeds programs must be stored in this memory while they are being executed.

Secondary memory: - Is used where large amounts of data & programs have to be stored, particularly information that is accessed infrequently. Examples: - Magnetic disks & tapes, optical disks (i.e. CD-ROM’s), floppies etc.

Question 25

In earlier computers what was the most common form of random access storage for computer main memory

Answer 25

It was an array of doughnut-shaped ferromagnetic loops referred to as cores.