Sistem Operasi untu materi kuliah sistem operasi

Slide sistem operasi

1. Input/Output

2. Objective

Issue commands to the devices

Catch interrupts

Handle errors

Provide user interface

3. I/O Device Classification

Based on data flow :
Block device

Save and transfer data as blocks, example :
disk, tape, CDROM, optical disk
Character device

Save and transfer data as character,
example : terminal, printer line, mouse

4. Basic Concept
-I/O device is connected to computer by port.
-Communicate with processor and other devices by bus.
-Communication between devices and processor – 2
methods – memory mapped and direct I/O instruction.
-Processor repeatedly checks for available access to
devices – polling
-I/O Device tells processor for available access –
interrupt

5. Register for I/O Port
- Data-in register
- Data-out register
- Status
- Control

6. Bus Structure

7. Processor – I/O Communication
1.Direct I/O instruction
each control register is assigned an I/O port number,
an 8- or 16-bit integer. Example : IN REG,PORT
(read), OUT PORT,REG (write)
2.Memory mapped
I/O registers are part of the regular memory address
space,
Direct I/O instruction Memory Mapped

8. Interrupt
Because of :
-Available to be accessed
-Output
-Error
Steps :
1.Controller sends interrupt signal using interrupt request line, detected by
processor
2.Processor saves the state of process and identify interrupt
3.Control transfer to interrupt handler
4.Processor continues its job

9. Direct Memory Access