DS/ISO/IEC 9318-4:2007

Information technology - Intelligent peripheral interface - Part 4: Device generic command set for magnetic tape drives (IPI-3 tape)

This part of ISO/IEC 9318 describes the logical level (generic level) interface for tape drives*and it provides a definition of the device-generic portion of a family of standards called the*Intelligent Peripheral Interface (IPI).*The purpose of this standard is to facilitate the development and utilization of an intelligent*interface which permits the interconnection of multiple peripheral types such as disk, tape and*communications to a controller.*The intent of the IPI is to isolate the host (CPU), both hardware and software, from changes in*peripherals by providing a function-generic command set to allow the connection of multiple*types of peripherals (disks, printers, tapes, communications). To smooth the transition from*the current methods to the generic approach, the IPI supports device-specific command sets*to aid in bridging the gap between the two approaches.*To accomplish this set of goals, the design of the IPI includes device-specific and devicegeneric*command sets. The device-specific command set provides:*- device-oriented control;*- physical data addressing;*- timing critical operations;*- lower device cost.*The device-generic command set provides a higher level of functionality and portability. It*includes:*- host/device independence;*- logical data addressing;*- timing independence;*- command queuing capability.*A system is not restricted to the use of one level of command set or the other. It is possible*that both levels of command sets will be utilized with a given system's architecture to balance*such parameters as system performance, cost and peripheral availability. It is also possible*for the host to provide for the migration from device-specific to device-generic levels while still*retaining the same physical interface.*The IPI standards family includes the definition of a high performance, general-purpose*parallel peripheral interface. However, the device-generic command set may also be*transported over other non-IPI physical interfaces. ANSI X3.291:1997 contains mappings to*the High-Performance Parallel Interface (HIPPI) and Fibre Channel (FC) as well as to the IPI*Enhanced Physical Interface. The mappings are not contained in this document.