1 Chapter 6 Computer Software

2 Manager’s View u Manager’s need to understand various kinds of computer software - makes the hardware work for you. u Understand the three broad categories of software and their uses: –Systems Software. –Application Software. –Development Software.

3 Management Concerns u Concern with site licensing versus installation on single workstations or servers. u Cost of upgrading hardware when new software is acquired. u Decision to build in-house versus buying a commercial package. u Developing company software standards.

4 Systems Software u Interfaces between computer system and application programs--written by systems programmers. –Operating Systems. –Communications Software. –Database Management Systems Software. –Other System Software.

5 Operating Systems u Manages/controls computer resources and peripherals, allocates memory, communicates to the computer operator. u Supervisory Programs: manages resources. u Job Management Programs: schedule jobs. u I/O Management Programs: handle input and output resources.

6 Resource Management u Multiprogramming: more than one program in memory at a time. u Timesharing: system moves from one program to another rapidly - like multiprogramming. u Multiprocessing: two or more CPUs working together sharing memory and peripherals. u Parallel Processing: two or more CPUs completing a single program. u Virtual Storage: moving data to hard disk temporarily.

7 Communications Software u An extension of the operating system. u Relieves operating system of the task of controlling peripherals. –Communicates with remote terminals. –Monitors lines and equipment. –Manages communications traffic.

8 Application Software u Performs specific functions, such as payroll; developed by application programmer. u Custom vs. Commercial: built in-house versus purchased as canned programs. u Shareware and Freeware: inexpensive sources of off-the-shelf application/systems utility programs.

9 Application Software (Cont.) u Application Program Library: the library of application programs available for a specific operating system. u Portability: version for many different operating systems; can be converted easily. u Single-User/Multiuser Programs: e.g., a word processing document that can be updated by several users simultaneously.

10 Application Software (Cont.) u Categorizing Application Software by Use: –General purpose software: used by people in different industries. –Functionally-specific software: designed for major functions such as financial analysis. –Industry-specific software: e.g., job estimating software for the construction industry.

11 Application Software (Cont.) u Desktop Suites: a family of packages such as Microsoft Office 97. –Word Processing Software: includes samples. –Spreadsheet Software: includes templates. –Database Management Software: sample databases. –Presentation Graphics: includes sample slides. –Add-On Software: e.g., ichat for the net.

12 Development Software u Allows programs and IS personnel to create custom software for specific types of jobs. u Programming Languages: used by application programmers.

13 Programming Languages u Machine Languages: lowest level language. u Assembly Languages: fast, but difficult to learn. u Third-Generation Languages: procedural-- tell computer exactly how to do tasks. u Fourth-Generation Languages: non- procedural--tell computer what to do, not how to do it.

14 Selecting Microcomputer Software u Step 1: Identifying Your Application Needs. u Step 2: Seeking the Right Software: check with trade associations; contact software companies; consult software databases; use the Internet; examine computer magazines; contact consultants. u Step 3: Choosing the Right Software: compare with your application requirements. u Step 4: Selecting the Right Hardware. u Step 5: Choosing a Software Vendor: look for established vendors with technical support.