Motorola MVME1X7P manual Parallel Printer Interface

Models: MVME1X7P

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Programming Issues

The CD2401 supports DMA operations to local memory. Because the CD2401 does not support a retry operation necessary to break VMEbus lockup conditions, the CD2401 DMA controllers should not be programmed to access the VMEbus. The hardware does not restrict the CD2401 to onboard DRAM.

Parallel (Printer) Interface

The PCCchip2 ASIC provides an 8-bit bidirectional parallel port. All eight bits of the port must be either inputs or outputs (no individual selection). In addition to the 8 bits of data, there are two control pins and five status pins. Each of the status pins can generate an interrupt to the MPU in any of the following programmable conditions: high level, low level, high-to-low transition, or low-to-high transition. This port may be used as a Centronics-compatible parallel printer port or as a general parallel I/O port.

When used as a parallel printer port, the five status pins function as: Printer Acknowledge (ACK), Printer Fault (FAULT), Printer Busy (BSY), Printer Select (SELECT), and Printer Paper Error (PE), while the control pins act as Printer Strobe (STROBE), and Input Prime (INP).

The PCCchip2 provides an auto-strobe feature similar to that of the MVME147 PCC. In auto-strobe mode, after a write to the Printer Data Register, the PCCchip2 automatically asserts the STROBEpin for a selected time specified by the Printer Fast Strobe control bit. In manual mode, the Printer Strobe control bit directly controls the state of the STROBEpin.

Refer to Chapter 3, PCCchip2 for detailed programming information. Refer to Appendix C, Related Documentation for drawings of the printer port interface connections.

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Motorola MVME1X7P manual Parallel Printer Interface