Sun Microsystems SPARCstation 20 - Sbus-To-External Bus Interface; FIGURE B-4 MACIO ASIC Functional Block Diagram

Appendix B Functional Description 203
FIGURE B-4 MACIO ASIC Functional Block Diagram
SBus-to-External Bus Interface
The SBus-to-external bus interface (SEC) ASIC provides the interface between the
SBus and the external bus. The external bus connects to the following:
■ Serial port chips (2)
■ Audio chip
■ Diskette drive controller
■ 4-Mbit EEPROM
■ NVRAM/TOD chip
■ LED interface
One of the serial port chips provides serial ports A and B. The second serial port
chip provides the keyboard and mouse port. Line drivers interface the two serial
port chips to the serial ports.
FIGURE B-5 illustrates a functional block diagram of the
SEC ASIC.
DMA
LANCE
Parallel
port
SCSI
Fast
SCSI
controller
AUI
TPE
Clock
chip
Parallel
port
SBus
MACIO ASIC