Diamond Systems Emerald-MM-DIO 4-Port RS-232 and 48 Digital I/O PC/104 Module

The Emerald-MM-DIO is a PC/104 module that combines four RS-232 serial ports with 48 digital I/O lines on a single board for embedded systems. It delivers serial communication via 16C554 UARTs supporting up to 115.2 Kbps (460.8 Kbps with optional crystal), plus individually programmable digital I/O with edge detection on 24 lines. The module fits the tight footprint constraints of PC/104 applications while providing industrial-temperature operation and full interrupt sharing across multiple ports. ## Technical Specifications Serial Ports • 4× RS-232 interfaces with 16C554 UARTs (16-byte FIFOs) • Data rates to 115.2 Kbps standard; 460.8 Kbps available with optional crystal • Full 8-signal set plus ground per port • Dual 20-pin (2×10) I/O headers at 0.1" centers • Jumper-selectable from 8 I/O address combinations and 11 interrupt levels • Interrupt sharing fully supported with dedicated status register Digital I/O • 48 lines organized into six 8-bit ports • Individual bit-level programmability for input or output • Inverting logic: logic 0 tri-states and pulls high via 10 kΩ resistor (input mode); logic 1 drives low • Output current: 0.3 mA (high state), 8 mA (low state) • Edge detection on 24 lines with selectable high/low edge triggering and interrupt generation • Two 2×25-pin I/O headers Physical & Electrical • Dimensions: 3.55" × 3.775" • Power: +5 VDC ±10%, 5V-only operation • Typical current draw: 80 mA (all outputs unloaded) • Operating temperature: −40°C to +85°C (extended versions available) • Humidity: 5% to 95% non-condensing ## Key Features • PC/104 form factor with 8-bit and 16-bit ISA bus headers • Bit-level input/output control eliminates need for external logic • Edge-triggered interrupts support event-driven application designs • Full interrupt sharing allows stacking multiple modules on single IRQ • Industrial temperature range for harsh environments ## Typical Applications Embedded data logging, industrial control interfaces, sensor array multiplexing, legacy serial device bridging, distributed I/O expansion in confined spaces. ## Compatibility & Integration Supports virtually all embedded operating systems via industry-standard PC/104 ISA interface. Universal Driver software provided for edge detection configuration and interrupt management.