ITC544 Study Notes

ITC544 Study Notes

Introduction ... 2

Data Representation ... 5

Boolean Algebra and Digital Logic ... 14

Simple Computer ... 31

Closer Look at Instruction Set ... 44

Memory ... 51

Input/Output and Storage Systems ... 60

System Software ... 64

Introduction

• Overview

◊ Computer organisation – how does a computer work?

- Encompasses all physical aspects of computer systems

§ i.e. circuit design, control signals, memory types - Computer architecture – how do I design a computer?

§ Logical aspects of system implementation as seen by the programmer

§ i.e. instruction sets, instruction formats, data types, address modes

• Computer Components

◊ No clear distinction between matters related to computer organisation and matters relevant to computer

- Principle of Equivalence of Hardware and Software

§ Any task done by software can also be done using hardware, and any operation performed directly by hardware can be done using software (assuming speed is not a concern)

ü Hardware – faster, expensive, single use ü Software – slower, cheaper, multiuse

◊ Three basic components of computer

- Processor – interpret and execute programs - Memory – store both data and programs

- I/O Mechanism – transferring data to and from the outside world

• An Example System

◊ Speed and Capacity Measure

one kibibit 1 Kibit 2¹⁰ bit 1024 bit one kilobit 1 Kbit 10³ bit 1000 bit one mebibyte 1 MiB 2²⁰ bit 1 048 576 B one megabyte 1 MB 10⁶ B 1 000 000 B

one gibibyte 1 GiB 2³⁰ B 1 073 741 824 B one gigabyte 1 GB 10⁹ B 1 000 000 000 B

◊ Hertz = clock cycles per second (frequency)

◊ Memory

- RAM – random access memory

§ Memory contents can be directly accessed if you know its location - Cache

§ Temporary memory that can be accessed faster than RAM

◊ Ports

- Serial – series of pulses along one or two data lines - Parallel – single pulse along eight data lines - USB – universal serial bus

§ Self-configuring

• Standards Organisations

◊ Assurances:

- Computer components operate as expected - Computer components will operate together

◊ IEEE – Institute of Electrical and Electronic Engineers

- Standards for computer components, data representation and signalling protocols - 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac

◊ ISO – International Organisation for Standardisation

- Influential in formulating standards for computer hardware and software, including their methods of manufacture

◊ ITU – International Telecommunications Union

- Interoperability of telecommunications systems

◊ ANSI – American National Standards Institute - BSI – British Standards Institute

• Historical Development

◊ Generation Zero: Mechanical Calculating Machines (1642 – 1945) - Calculating Clock – Wilhelm Schickard

- Pascaline – Blaise Pascal

- Difference Engine – Charles Babbage

- Punched Card Tabulating Machines – Herman Hollerith

§ Hollerith cards were commonly used for computer input well into the 1970s

◊ First Generation: Vacuum Tube Computers (1945 – 1953)

- Atanasoff Berry Computer – solved systems of linear equations

§ John Atanasoff and Clifford Berry

§ Iowa State University

- ENIAC – Electronic Numerical Integrator and Computer

§ First general-purpose computer

§ John Mauchly and J Presper Eckert

§ University of Pennsylvania - IBM 650

§ First mass-produced computer

◊ Second Generation: Transistorised Computers (1954 – 1965) - Transistor – transfer resistor – solid state triode - Systems had few architectural similarities

◊ Third Generation: Integrated Circuit Computers (1965 – 1980)

Name Year Transistors Logic Gates

Small Scale Integration (SSI) 1964 1 to 10 1 to 12

Large Scale Integration (LSI) 1971 500 to 20,000 100 to 9999 Very Large-Scale Integration

(VLSI)

1980 20,000 to 1,000,000

10,000 to 99,999 Ultra Large Scale Integration

(ULSI)

1984 >1,000,000 >100,000

- Introduction of time-sharing and multi-programming (multiple users)

◊ Fourth Generation: VLSI Computer (1980 – ???) - VLSI – Very large scale integrated circuits

§ >10,000 components per chip

§ Enabled microprocessor creation

§ Spawned “personal computer”

◊ Moore’s Law

- “The density of silicon chips doubles every 18 months” – Gordon Moore, Intel founder

- “The cost of capital equipment to build semiconductors will double every four years” – Arthur Rock, Intel financier

- Only one law can hold

• The Computer Level Hierarchy

Level 6 User Executive Programs

Level 5 High-Level Language C++, Java, FORTRAN Level 4 Assembly Language Assembly Code

Level 3 System Software Operating System, Library Code Level 2 Machine Instruction Set Architecture Level 1 Control Microcode or Hardwired Level 0 Digital Logic Circuits, Gates

• The Von Neumann Model

◊ Stored-program computers

◊ Characteristics:

- Three hardware systems:

§ CPU

§ Main Memory

§ I/O

- Sequential instruction processing - von Neumann bottleneck

§ Single data path between the CPU and main memory

Data Representation

• Introduction

◊ Bit – smallest unit of information

- State of “on” or “off” in digital circuit

◊ Byte – smallest addressable unit of computer storage - Group of eight bits

- Addressable – can be retrieved according to memory location

◊ Word – contiguous group of bytes

- Word sizes of 16, 32 and 64 bits are most common

- In word-addressable system, word is smallest addressable unit of storage

◊ Nibble - group of four bits - Bytes = two nibbles

§ High-order nibble and low-order nibble

• Positional Numbering Systems

◊ Binary system – base-2

◊ Decimal system – base-10

• Converting Between Bases

◊ Converting Unsigned Whole Numbers - Two methods for radix conversion

§ Subtraction method 54_#$= '₍ 054

−32 = 2^-× 1 022

−16 = 2¹× 1 006

− 0 = 2²× 0 006

− 4 = 2⁽× 1 002

− 2 = 2^#× 1 000

− 0 = 2^$× 0 000

54_#$= 110110₍

§ Division reminder method 54_#$= '₍