1. Lally School of M&T Pindaro Demertzoglou 1 Computer Software

2. Lally School of M&T- Microcomputing and Info Sys Lecture Topics 2 1. Industry Overview 2. Operating System Software 3. Application Software 4. Programming Languages

3. Lally School of M&T- Microcomputing and Info Sys Industry Overview 3 Software Production in the US involves 50,000 companies. 50% of sales from packaged programs and 50% from custom programming. In the packaged programs market the top 50 companies hold 70% of the market. Sales and Marketing Expenses exceed 30% of revenues.

4. Lally School of M&T- Microcomputing and Info Sys Software Categories Chapter 3: Computer Software 4

5. Lally School of M&T- Microcomputing and Info Sys Operating System Software 5 Intermediary between Application Software and Computer Hardware Program Management Scheduling Programs Monitoring Programs Resource Management Control system resources (Primary storage, secondary storage, CPU time) Data Management Controls location, storage, and retrieval of data

6. Lally School of M&T- Microcomputing and Info Sys Operating System Software 6 Multiprogramming Two or more applications placed in memory at the same time. Program two is executed when an interruption occurs to program one. Switching is very fast and it appears that programs execute simultaneously. Multiprogramming is a software implementation only. Multiprocessing More than one processor is involved. The OS has the ability to work with multiple processors. Multiprocessing is a hardware/software configuration.

7. Lally School of M&T- Microcomputing and Info Sys Where is the operating system stored? 7 The OS’s small bootstrap program resides in ROM and supplies the instructions to load the core parts into memory when the system boots This component is called the kernel

8. Lally School of M&T- Microcomputing and Info Sys Market Share of OSs 8 http://marketshare.hitslink.com/

9. Lally School of M&T- Microcomputing and Info Sys Programming Languages 9 First Generation – Machine Language Program in 0s and 1s All languages are ultimately translated to machine language since 0s and 1s is only what the computer understands Machine languages are hardware dependent Second Generation – Assembly Language – Programmer friendlier – uses mnemonics – Hardware dependent. The example on the right is for an Intel 80186 or higher

10. Lally School of M&T- Microcomputing and Info Sys Programming Languages 10 Third Generation Basic, Cobol, Fortran, Prolog Require the programmer to write code statements line by line. Fourth Generation – Non procedural SQL languages Interested in the result, not the code in between Fifth Generation Natural Language Programming Languages Improve the user interface

11. Lally School of M&T- Microcomputing and Info Sys Compilers - Interpreters Compiler transforms source code to object code (i.e. programmer code to machine code) Interpreters: A kind of compiler that translates one statement at a time at real time. Simpler than compilers Slower than compilers