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Understand I/O in Computer System, CHARACTERISTICS OF ISOLATED AND MEMORY…
Understand I/O in Computer System
INTRODUCTION
The term I/O is used to describe any program, operation or device that transfers data to or from a computer and to or from a peripheral device
Devices such as keyboards and mouses are input-only devices while devices such as printers are output-only. A writable CD-ROM is both an input and an output device
FUNCTION
Acts as an interface with the CPU and memory via the system bus or central switch
Acts as an interface with one or more peripheral devices by tailored data links
DEVICES
INPUT DEVICES
Keyboard
Mouse
Scanner
Microphone
Joystick
OUTPUT DEVICES
PRINTER
PROJECTOR
MONITOR
SPEAKER
HEADPHONE
INPUT/OUTPUT DEVICES
MODEM
FAX
WEBCAM
INPUT OUTPUT DATA TRANSFER
Asynchronous Communication Interface
asynchronous communication is transmission of data, generally without the use of an external clock signal, where data can be transmitted intermittently rather than in a steady stream
Asynchronous Serial Transfer
Asynchronous serial communication is a form of serial communication in which the communicating endpoints' interfaces are not continuously synchronized by a common clock signal
TRANSFER MODE
PROGRAMMED I/O
Is the method of transferring data between the CPU and a peripheral such as a network adapter or an ATA storage device
INTERRUPTED-INIATED I/O
Overcomes the process having to wait long periods of time for I/O modules the processor does not have to repeatedly check the I/O module status
DIRECT MEMORY ACCESS
a method of transferring data between peripherals and memory without using the CPU. A special-purpose processor called a DMA controller(DMAC) can be used to transfer data between memory and I/O devices
CHARACTERISTICS OF ISOLATED AND MEMORY MAPPED I/O
MEMORY MAPPED
Devices and memory share an address space
I/O looks just like memory read/write
No special commands for I/O
Large selection of memory access commands available
ISOLATED
Separate address spaces
Need I/O or memory select lines
Special commands for I/O
Limited set