The document discusses input/output devices, modules, and techniques in a computer system. It describes human readable devices like displays and printers, machine readable devices like magnetic disks and sensors, and communication devices. It then explains the functions of I/O modules like control and timing, processor communication, device communication, data buffering, and error detection. Finally, it outlines different I/O techniques: programmed I/O where the processor directly controls operations, interrupt-driven I/O where the processor is interrupted to handle I/O, and direct memory access where the I/O module accesses memory directly without involving the processor.

1. INPUT OUTPUT
1- Devices
2- Modules
3- Techniques

2. GROUP MEMBERS
• Ammar Shaukat
• Sadam Husain
• Taimur Hassan
11011519-073
11011519-037
NOT FOUND

3. INPUT OUTPUT DEVICES
•Human Readable
•Machine Readable
•Communication

4. HUMAN READABLE
1-Interact with human
e.g, video display termilnals , Printers

5. MACHINE READABLE
•Communicate with equipment
•E.g, Magnetic disk , tape , DVD
, Sensors etc

6. COMMUNICATION
•Communicate with remote devices
•
Structure:

7. EXTERNAL DEVICES

8. INPUT OUTPUT MODULES
•Functions
•Structure

9. MODULES FUNCTOINS
•Control And timing
•Processor Communication
•Device Communication
•Data Buffering
•Error Detection

10. CONTROL AND TIMING
• To coordinate the flow of traffic between
internal resources and external devices.
• E.g,
Switching of task from execution to I/0

11. PROCESSOR COMMUNICATION
• I/O Module must communicate with the
processor and with the external device.
• Command decoding:
( module accepts the command from
processor and sent signals on control bus )
e,g READ , WRITE , SCAN etc

12. PROCESSOR COMMUNICATION
• Data:
( exchange of data between Processor and
module )
• Status reporting: ( BUSY , READY )
• Address recognition:
( I/O Module must recognize a unique address for
each Peripheral it controls )

13. DEVICE COMMUNICATION
• I/O Module must be able to perform
device communication
This involve
• Commands
• Status
• Data

14. DATA BUFFERING
• I/O Module must be able to
communicate at both Device and
Memory Speeds

15. ERROR DETECTION
• Different error detection techniques used
• Report error: bad disk track or paper jam
• Error techniques: Parity bit etc

16. MODULE STRUCTURE
• Signal Lines (system bus lines):
Connection with rest of computer
• Logic:
Interact with the processor
Sturcture

18. INPUT OUTPUT TECHNIQUES
•Programmed I/O
•Interrupt Driven I/O
•Direct Memory Access

19. PROGRAMMED I/O
• Sequential manner Processing with module
• Direct control of Input output operation
• Disadvantage: Processor time wastage

20. INTERRUPT DRIVEN I/O
•Processor Issues a command to I/O
module and continues other
instructions
Does not wait completion of that I/O
operation.

21. DISADVANTAGE
INTERRUPT DRIVEN I/O
• Processor time wasting but less than
programmed…
• Processor keeps engaged in every read or
write operation from input output module.

22. DIRECT MEMORY ACCESS
• Module access the main memory directly
without involving the processor.
• And processor continue its execution without
interruption after reading or writing a word.

23. DIRECT MEMORY ACCESS