have protocols
– interfaces for device I/O
have dedicated handlers
– device drivers, interrupt handlers…
decouple I/O details from core processing
input: keyboard, microphone
output: speaker, display
both of them: network interface card, flash card, hard disk drive
Basic I/O device features
control register
-command, data transfers, status
internal:micro-contorller, memory, other hardware-specific chips
microcontroller == device’s CPU
on device memory
other logic e.g. analog to digital converters
Peripheral component Interconnect(PCI)
-PCI Express(PCIe) (> PCI-x > PCI)
Other types of interconnects
-scsi bus
-peripheral bus
-bridges handle differences
Device Drivers
-per each device type
-responsible for device access, management and control
-provided by device manufacturers per os/version
