17-08-2012, 03:40 PM
CD-Rom Driver
CD-Rom.ppt (Size: 30.5 KB / Downloads: 26)
What is an O.S.?
Not always a clear definition as to what constitutes an O.S. and what is an application
CD-Rom Driver
Scandisk
Internet Explorer
Intermediary between the hardware and the users
Allocate resources (CPU, Memory, disk space, etc.) between programs and users efficiently
Allow the user to conveniently access data and programs
Protect the system from incorrect or malicious programs and users
Hardware Review
Elements of a system
Processor
Registers (address, data, control)
Instruction cycle (fetch, decode, execute)
Interrupts
Usually includes hardware and special instructions to help the O.S. manage memory, devices, etc.
Memory
Different levels (cache, main memory, disk)
Operating system will generally manage memory (both RAM and disk), and move data back and forth as required
I/O
Usually use Interrupts, DMA
Operating system usually controls use of I/O devices
Registers
Used for frequently accessed items
User-Visible registers – Available to the programmer and compiler
Data Registers
Address Registers
Index, Segment, Stack Pointer
Condition code/flags
Control and Status registers – Used to control the processor
Program Counter/Instruction Pointer
Memory address/data
Processor Status Word
Debugging registers
Temp registers
Memory Management registers