Sun Microsystems 220R service manual Scsi

MII is used to interconnect both integrated circuits and circuit assemblies. This enables separate signal transmission paths to exist between the reconciliation sublayer, embedded in the PCIO ASIC, and a local PHY IC, and between the reconciliation sublayer and a remote PHY IC. The unidirectional paths between the reconciliation sublayer and the local PHY IC are composed of sections A1, B1, C1 and D1. The unidirectional paths between the reconciliation sublayer and the remote PHY IC are composed of sections A2, B2, C2, and D2.

C.1.11 SCSI

The system unit implements a small computer system interface (SCSI) Fast-20 (UltraSCSI) parallel interface bus. The UltraSCSI provides the following:

Efficient peer-to-peer I/O bus devices

Mechanical, electrical, and timing specification definition that support transfer rates of 20 or 40 Mbytes per second (corresponding to the data path width of an

48-bit, or 16-bit bus, respectively)

Peak bandwidth of 40 Mbytes per second (with implemented 16-bit bus width)

The internal SCSI bus is terminated at each end. One set of terminators is located close to the CD-ROM drive connector on the CD-ROM SCSI card. A second set of terminators is located close to the 68-pin external SCSI connector.

268 Sun Enterprise 220R Server Service Manual ♦ January 2000, Revision A