Motorola MVME2603-1121A, Инструкция по установке и эксплуатации

Страница: 179 / 210

C
C-1
C 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
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 10MHz clock to implement the
two synchronous/asynchronous serial communications ports,
which are routed through P2 to the transition module. The Z85230