The ST-BUS Parallel Access Circuit (STPA) provides a simple interface between Mitel’s ST-BUS and parallel system environments. It features high-speed parallel access to the serial ST-BUS, optimized for 68000 µP, fast dual-port RAM access, flexible interrupt capabilities, selectable channel operation, programmable loop-around modes, and low power CMOS technology.
The document describes the Mitel MT8920B, a CMOS device that provides a simple interface between Mitel's ST-BUS and parallel system environments. It supports high-speed parallel access to serial data streams at 2048 kbit/s and is optimized for 68000 microprocessors or dual-port RAM applications.
The datasheet outlines three distinct modes of operation: Peripheral Mode (Mode 1) which acts as a 68000-type peripheral with interrupt capabilities; Fast RAM Mode (Mode 2) intended for high-speed data access to internal RAMs; and Bus Controller Mode (Mode 3) which drives the parallel bus without an external controller. It includes detailed pin descriptions, functional block diagrams, and ordering information.
| Access time | 120 nsec |
|---|---|
| Technology | Low power CMOS technology |
| Clock frequency | 4.096 MHz |
| Data rate | 2048 kbit/s |
| Power supply voltage | +5V |
The access time for the device is 120 nsec.
The device supports selectable 24 and 32 channel operation.