input output devices and modules in computer
DESCRIPTION
its about Computer Architecture input output devices and input output modulesTRANSCRIPT
INPUT OUTPUT1- Devices2- Modules3- Techniques
GROUP MEMBERS•Ammar Shaukat 11011519-073•Sadam Husain 11011519-037•Taimur Hassan NOT FOUND
INPUT OUTPUT DEVICES
•Human Readable•Machine Readable•Communication
HUMAN READABLE
1-Interact with humane.g, video display termilnals , Printers
MACHINE READABLE
•Communicate with equipment•E.g, Magnetic disk , tape , DVD , Sensors etc
COMMUNICATION•Communicate with remote devices
• Structure:
EXTERNAL DEVICES
INPUT OUTPUT MODULES
•Functions•Structure
MODULES FUNCTOINS
•Control And timing•Processor Communication•Device Communication•Data Buffering•Error Detection
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
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
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 )
DEVICE COMMUNICATION• I/O Module must be able to perform device communication
This involve•Commands•Status •Data
DATA BUFFERING
• I/O Module must be able to communicate at both Device and Memory Speeds
ERROR DETECTION
•Different error detection techniques used•Report error: bad disk track or paper jam•Error techniques: Parity bit etc
MODULE STRUCTURE•Signal Lines (system bus lines): Connection with rest of computer •Logic: Interact with the processor Sturcture
INPUT OUTPUT TECHNIQUES
•Programmed I/O•Interrupt Driven I/O•Direct Memory Access
PROGRAMMED I/O•Sequential manner Processing with module•Direct control of Input output operation
•Disadvantage: Processor time wastage
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.
DISADVANTAGEINTERRUPT DRIVEN I/O
•Processor time wasting but less than programmed…•Processor keeps engaged in every read or write operation from input output module.
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.
DIRECT MEMORY ACCESS