1. Introduction to Humanities Computing Spring 1999 Lecture Nine

2. Operating Systems F CPM (control program for microcomputers) F DOS, F Windows F Windows 95 F Windows NT F Mac OS F UNIX

3. History F CP/M http://www.geocities.com/SiliconValley/5711/history.html F BIOS component of CP/M Basic Input Output System Why is this development important?

4. Purpose F Manage Files and Programs F Manage Devices F Manage Network Connection F Allow programs to talk to each other F Provide standard code (windows, text fields) Operating systems

5. Manage Files and Programs In multitasking operating systems where multiple programs can be running at the same time, the operating system determines which applications should run in what order and how much time should be allowed for each application before giving another application a turn. whatis.com

6. Manage Devices Operating systems handle input and output to and from attached hardware devices, such as hard disks, printers, and dial-up ports. whatis.com

7. Error Catchers Operating systems send messages to the applications or interactive user (or to a system operator) about the status of operation and any errors that may have occurred. whatis.com

8. Information Interchange F Codes & Operating systems UNIX and DOS-based operating systems (except for Windows NT) use ASCII for text files. Windows NT uses a newer code, Unicode. IBM's System 390 servers use a proprietary 8-bit code called EBCDIC. F Conversion programs allow different operating systems to change a file from one code to another.

9. Boot, Run, Open F Your computer typically comes with the OS installed. F You install the applications F You launch (run) applications F You create documents with the applications F You manage the documents (files) with the File Management tools in the OS.

10. Interface F How the computer is designed to interact with humans. F What does it show? F What does it allow users to do? F How does it communicate with users? F How does it represent the internals of the computer?

11. Lippman on Interactivity Mutual and simultaneous activity on the part of both participants usually working towards some goal but not necessarily Stewart Brand The Media Lab: Inventing the Future at M.I.T p.46

12. Lippman’s 5 corollaries Interruptablitiy Graceful degradation Limited look ahead No default Impression of infinite database

13. Designer Question Are Lippman’s corollaries the best way to judge an operating system ?