Week 3

Question 1

What are the main parts of a computer?

Answer 1

It’s a machine that executes sequences of instructions (which are programs) that are directed to work on data coming in (which is binary code). The data coming out will also be binary coded.

Question 2

What are the computer subsystems?

Answer 2

1) Processor (at the core) or CPU. The processor fetches, decodes and executes sequences of binary coded instructions. The processor controls the fetch of the instructions.
2) Instruction memory - where a program is stored as a list of machine code instructions.
3) Data memory - code words representing data are stored here. It will store intermediary results here.
4) input/output subsystem
5) system interconnect - allows the various components to communicate. This is usually implemented as one or more buses.

Question 3

What kind of information can electronic memory store?

Answer 3

binary coded information

Question 4

Do all addresses have the same length of bits in memory?

Answer 4

Yes. The longer the number of bits, the more addresses we can have.

Question 5

If we have an address where there’s no memory cells there, what do we say about the addresses?

Answer 5

They are unpopulated. Unpopulated addresses cannot stope anything. large address spaces are only party populated

Question 6

How is data memory organised?

Answer 6

By indexed arrays of registers called locations, each labelled by an unsigned binary index or address.

Question 7

What does the CPU do when it want to read data from memory?

Answer 7

The CPU will generate an address when it wants to read from or write to a location.

Question 8

What is the address space?

Answer 8

The address space is the set of all addresses CPU can generate is its address space.

Question 9

What is primary memory?

Answer 9

Randomly addressable memory such as that used for instructions and data. These are stored there as binary coded words.

Question 10

In most current computers, the instructions and data are stored in a single address space (often on the same chips) accessed using the same buses. What is this called?

Answer 10

von Neumann or Princeton architecture.

Question 11

In most current computers, the instructions and data are stored in a single address space (often on the same chips) accessed using the same buses. What is it called when the instructions and data are stored on separate addresses and spaces?

Answer 11

Harvard architecture.

Question 12

What does it mean to say physical memory is volatile?

Answer 12

If it’s content is lost when power is removed. Non-volatile memory doesn’t need power at all.

Question 13

Is read only memory (ROM) volatile or non-volatile?

Answer 13

non-volatile

Question 14

Is random access memory (RAM) volatile or non-volatile?

Answer 14

volatile. RAM is read/write memory.

Question 15

What is flash memory?

Answer 15

It’s non-volatile.
Slower than RAM.
It’s used in things like solid state drives.

Question 16

What is secondary memory in computers?

Answer 16

Usually in the form of disks or other mass storage devices.

Question 17

What is the CPU?

Answer 17

• a compound subsystem of the computer.
• inside every processor there is:
  1) a control unit (CU) - co-ordinates the activities of the processor as a whole. It ultimately controls the computers as well. It examines the instructions and co-ordinates the other systems to execute them.
  2) An execution unit (EU) - contains hardware to perform operations on binary words.
  3) A register file consists of a set of general registers for holding data or addresses. It’s a device that can store a binary word. Supplies code words to the execution unit.
  4) A bus interface - an interface to the external address and data buses through which the CPU communicates with primary memory and I/O interfaces.

Question 18

What do we call a processor (CPU) on a single chip?

Answer 18

microprocessor

Question 19

What is a microcomputer unit?

Answer 19

A complete computer (including memory and CPU) on a single chip

Question 20

What is the control unit?

Answer 20

It is in the CPU, and it co-ordinates the activities of the processor. It also contains special-purpose registers.

Question 21

What is the program counter?

Answer 21

It’s a special register that’s found in the control unit (in the CPU). It points to the next address once the previous instruction has been fetched.

Question 22

What is the instruction cycle?

Answer 22

The sequence of fetching, decoding and execution

Question 23

What is the arithmetic logic unit?

Answer 23

It can do simple boolean logic operations and it resides in the execution unit (in the CPU).

Question 24

What are the two categories of CPU registers?

Answer 24

1) Registers in the register file for general use by instructions and are numbered.
2) Special purpose registers usually associated directly with the CU (control unit).

Question 25

What are the two kinds of special purpose register?

Answer 25

1) Registers that contain useful info at the end of an instruction. The status register captures all the flags (eg overflow, z-bit) from the last instruction.
2) Registers which are only used inside an instruction and have no useful info after the instruction finishes execution.

Question 26

What does the compiler do in high level languages such as C and Java?

Answer 26

It translates the code written into machine code. A compiler must generate machine code for a specific CPU type

Question 27

What is programmer’s model?

Answer 27

It’s the set of CPU registers that can be used to carry info from one instruction to another.

Question 28

What does the instruction register hold?

Answer 28

The machine code instructions that is fetched from memory while the processor is figuring out what it is.

Question 29

Look over instruction cycle diagram from slide 11 lecture 3 and outline each of the stages.

Answer 29

see slide 11 and 14 of lecture 3

Question 30

What is sigma 16?

Answer 30

It’s a microprocessor.