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The terms describe fast-access storage, as opposed to auxiliary storage, such as that provided by direct-access storage devices. (p3-2)
Chapter 13 I/O Overview
- I/O devices are attached through control units to the channel subsystem via channel paths. (p13-1)
- I/O devices include such equipment as printers, magnetic-tape units, direct-access-storage devices, ... (p13-4)
- An I/O device may be physically distinct equipment, or it may share equipment with other I/O devices. (p13-5)
- A device identifier is an address, not apparent to the program, that is used by the channel subsystem to communicate with I/O devices. (p13-6)
- The device address identifies the particular I/O device ... The device address may identify, for example, a particular magnetic-tape drive, disk-access mechanism ... (p.13-6)