Motorola MVME2600 manual Asynchronous Serial Ports, Synchronous Serial Ports

BSerial Interconnections

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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

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