Computer Basics. Rabie A. Ramadan, PhD 5. Computer Software. Computer Software. What we’ll cover for this lecture topic: Software categories Applications software Systems software What is an operating system ? What does it do for me? What does it do for application programs?
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Rabie A. Ramadan, PhD
What we’ll cover for this lecture topic:
• printout out paychecks • play Mortal Kombat • keep track of a stamp collection • do your taxes • generate a fancy newsletter • guide robots • keep a budget • draw a flowchart • browse the Web • design a car
System softwareHelps computer carry out its basic tasks.
WORD called on O.S. to present you with that file list!
FAT (copy 2)
FAT (copy 1)FAT eliminates a real problem ….
You Save a file.
Later, ADD several pages to the file.
YOU SAVE AGAIN (same name).
No free clusters nearby! What now?
OS checks FAT for open clusters, stores rest of file there, adds pointers to FAT which will link these non-contiguous clusters to that file.
BUT! what will happen to your disk over time? So what?
“Shutting down incorrectly is a little like stopping your car by driving it into a wall. It works, but it can cause some damage.” (author unknown)
I/O Terminals (multiple users)Manages/allocates time & memory space
Run two or more programs concurrently.
eg: Calculate payroll and Accts payable and WP and …
1. Multi-user OS(eg: Unix).
(“Hard boot”). LAST RESORT!
Find and print the names of all freshmen who scored greater than 79% on the first exam.
Assembly:LDR A5FD R1 More readable form of binary;
CMP R1, 1 … symbolic representation.
ML:00000010 10001100 01100000 00010001 00000111 ...