Chapter 2

Introduction to Systems Architecture

Chapter goals Discuss the development of automated computing Describe the general capabilities of a computer Describe computer system components and their

functions List computer system classes and their distinguishing

characteristics Define the role and function of application and

system software Describe the economic role of system and application

development software

Why invent a computer? What kinds of problems were

people trying to solve?

Primary characteristics of a computer General-purpose processor capable of

performing computation, data movement, comparison, and branching functions

Storage capacity sufficient to hold large numbers of program instructions and data

Flexible communication capability through the use of multiple media and devices

Computer hardware

CPU Architecture

Storage Categories

Input/output capacity PC is a varied collection of devices

connected through internal communication (system bus)

Readings from White on evolution of the system bus

System bus How does capacity of system bus

compare to CPU? Why is “backwards compatibility”

an important issue for the bus?

Computer System Classes Microcomputer/Network Computer (PC) Minicomputer (up to 100 simultaneous users) Mainframe (1000s of simultaneous users) Supercomputer (computationally intense

applications – weather forecasting, computer animation)

Computer System Classes

The Role of Software

Complexity of software creationSoftware performs a complex translation: Identified need or task Human language description of how to

complete the task (algorithm, recipe, construction plan, blueprint)

Algorithm to programming language (code) Programming language to machine language Machine language to CPU instructions (all

binary, 0s and 1s)

Software types Application software System software

Systems software Invisible to user (ideal) IS professional – needs to

understand/configure/install/maintain/update systems software

Software layers

Software/hardware layers

System software layers System management – utilities called by

user/system administrator System services – functions common to

many applications carried out by system software (print)

Resource allocation – manage multiple requests for same resource

Hardware interface – carries out instructions that operate directly on devices (device drivers)

Machine independence Layers “hide” specific details about

hardware Standard service requests (print) are

translated at lowest possible level to specific hardware instructions

Example: adding a new printer changes your OS, not every application installed on your machine

Machine independence (cont.) Placing all hardware interface

functions within a single system software layer

Concept of virtual machine (used by Java, .NET) Same applet is downloaded Each individual machine (unix, mac,

windows) has own systems level to carry out instructions from applet

Operating systems functions Program storage, loading and

execution File manipulation and access Secondary storage management Network and interactive user

interfaces

Application development Toolkit or suite to assist in

development of software Referred to as Integrated

Development Environment (IDE) Programs that helps create other

programs

Application development (cont.)

IDE consists of Program translator (compiler) Program editors Debugging tools System development & modeling

tools (CASE computer aided software engineering)

Computer networks Set of hardware and software

components that allows information, software and hardware resources to be shared among multiple users and computer systems

Network components

External Resources Network Software Network Communication and the

Physical Network

Chapter summary This chapter introduces the

primary topics of the text: Hardware Processor Software Operating systems Networks