It manages system resources 4. Monitors performance of system 5. Prompts error messages. Multi tasking means an SO can run more than one program at a time Basic systems that are not multi tasking are called single program mode Ox’s. User interfaces Can be command driven-blank screen and commands and code used. Can be menu driven- headings and menus Most common is GIG-II-graphical user interface-combines menu driven and cons- Guy’s are known as WIMPS-windows, icons, menus, pointers Data capture Data capture turns info into data Automatic data capture-is fast and accurate BUT manual data capture- is necessary sometimes, and it’s cheaper!
Data validation and verification Validation-4 checks Range check-checks data is in specified range Presence check-makes sure data is present Check digit-check that numerical data is accurate Data type-checks that text is not where numbers are meant to be. Verification-2 checks Proof reading-read it and make sure that its accurate Double-entry-data entered twice and compared. Validation problems- mistakes may be allowed if carried out wrong and only makes sure that data is right type. Verification problems-double entry is time consuming-expensive and proof reading is time consuming and does not eliminate human error.
Data processing Real time processing does it instantly Batch processing-all in one go Transaction processing-one off specials Interactive processing-talk to the computer Access to data Serial access-records are stored one after another in creation order Sequential access-records are stored one after another AC. To sensible order Direct access-can go to record directly Implementation and evaluation 3 types of implementation- Direct-straight away and old system goes down but bugs not picked up in testing-bad news!
Phased-different parts are introduced one at a time Old system is kept running Parallel-new system is introduced in one go BUT old system stays New system can be tested quickly but all tasks need to be done twice.