B
B-1
B
Serial Interconnections
Introduction
As described in previous chapters of this manual, the MVME2603/2604
serial communications interface has four ports. Two of them are combined
synchronous/asynchronous ports; the other two are asynchronous only.
Both synchronous and asynchronous ports supply an EIA-232-D
DCE/DTE interface via P2 and the MVME712M transition module.
Asynchronous Serial Ports
The MVME2603/2604 uses a PC87308 ISASIO chip from National
Semiconductor to implement the two asynchronous serial ports (in
addition to the disk drive controller, parallel I/O, and keyboard/mouse
interface).
The asynchronous ports provided by the ISASIO device are routed through
P2 and the associated transition module. The TTL-level signals from the
ISASIO chip are buffered through TTL drivers and series resistors, then
routed through EIA-232-D drivers and receivers to complete the
asynchronous serial interface enroute to the MVME712M transition
module.
The MVME2603/2604 hardware supports asynchronous serial baud rates
of 110B/s to 38.4KB/s. For detailed programming information, refer to the
PCI and ISA bus discussions in the MVME2600 Series Single Board
Computer Programmer’s Reference Guide, listed in
Appendix D, Related
Documentation
, and to the vendor documentation for the ISASIO device.
Synchronous Serial Ports
The MVME2603/2604 uses a Zilog Z85230 ESCC (Enhanced Serial
Communications Controller) with a 10 MHz clock to implement the two
synchronous/asynchronous serial communications ports, which are routed
through P2 to the transition module. The Z85230 handles both
