Sun Microsystems SPARCstation 20 - Sbus-To-SCSI, Ethernet, and Parallel Interfaces

202 SPARCstation 20 Service Manual • July 1996
NVSIMM
The NVSIMM provides an interface to the Prestoserve™™ software. The NVSIMM
furnishes a battery backed-up memory that is used as a cache for disk drive access.
Operating conjointly with the Prestoserve software, the NVRAM accelerates both
NFS and UFS disk access. The maximum available NVSIMM memory capacities
based upon possible memory allocations is 2 Mbytes.
SBus-to-SCSI, Ethernet, and Parallel Interfaces
The SBus-to-SCSI, Ethernet, and parallel interface (MACIO) ASIC provides the
interface between the SBus and the following:
■ SCSI
■ Thick AUI Ethernet
■ Twisted-pair Ethernet (TPE)
■ Parallel port
The MACIO ASIC integrates three functions:
■ Direct memory access (DMA)
■ Local area network control for Ethernet (LANCE)
■ Fast SCSI bus interface
FIGURE B-4 illustrates a functional block diagram of the MACIO ASIC.