ch11[1] - Computer System Architecture Dept. of Info. Of...

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Unformatted text preview: Computer System Architecture Dept. of Info. Of Computer. Chap. 11 Input-Output Organization Chap. 11 Input-Output Organization 11-1 11. Input-Output Organization ■ 11-1 Peripheral Devices I/O Subsystem ● Provides an efficient mode of communication between the central system and the outside environment Peripheral ( or I/O Device ) ● Input or Output devices attached to the computer » Monitor ( Visual Output Device ) : CRT, LCD » KBD ( Input Device ) : light pen, mouse, touch screen, joy stick, digitizer » Printer ( Hard Copy Device ) : Dot matrix ( impact ), thermal, ink jet, laser ( non-impact ) » Storage Device : Magnetic tape, magnetic disk, optical disk ASCII ( American Standard Code for Information Interchange ) Alphanumeric Characters ● I/O communications are usually involved in the transfer of ASCII information ● ASCII Code : Tab. 11-1 » 7 bit o& : 00 - 7F ( 0 - 127 ) ■ 80 - FF ( 128 - 255 ) : Greek, Italic, Graphics, ¤ ¡ ¢ „ “ && ■ 11-2 Input-Output Interface Interface + ¢ „ “ ● 1) A conversion of signal values may be required Computer System Architecture Dept. of Info. Of Computer. Chap. 11 Input-Output Organization Chap. 11 Input-Output Organization 11-2 ● 2) A synchronization mechanism may be needed » The data transfer rate of peripherals is usually slower than the transfer rate of the CPU ● 3) Data codes and formats in peripherals differ from the word format in the CPU and Memory ● 4) The operating modes of peripherals are different from each other » Each peripherals must be controlled so as not to disturb the operation of other peripherals connected to the CPU Interface ● Special hardware components between the CPU and peripherals ● Supervise and Synchronize all input and output transfers I/O Bus and Interface Modules : Fig. 11-1 ● I/O Bus » Data lines » Address lines » Control lines ● Interface Modules : o& VLSI Chip i » SCSI (Small Computer System Interface) » IDE (Integrated Device Electronics) » Centronics » RS-232 » IEEE-488 (GPIB) Interface Keyboard and display terminal Interface Magnetic tape Interface Magnetic disk Interface Printer Processor Data Control Address I/ O bus Computer System Architecture Dept. of Info. Of Computer. Chap. 11 Input-Output Organization Chap. 11 Input-Output Organization 11-3 ● I/O command : 8251 SIO o& » Control Command » Status Command » Input Command » Output Command I/O Bus versus Memory Bus ● Computer buses can be used to communicate with memory and I/O » 1) Use two separate buses, one for memory and the other for I/O : Fig. 11-19 , p. 421 ■ I/O Processor » 2) Use one common bus for both memory and I/O but have separate control lines for each : Isolated I/O or I/O Mapped I/O ■ IN , OUT : I/O Instruction ■ MOV or LD : Memory read/write Instruction » 3) Use one common bus for memory and I/O with common control lines : Memory Mapped I/O ■ MOV or LD : I/O and Memory read/write Instruction Intel, Zilog...
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This note was uploaded on 03/21/2010 for the course CS 145 taught by Professor Markjan during the Spring '10 term at Abilene Christian University.

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ch11[1] - Computer System Architecture Dept. of Info. Of...

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