MIDI-Mite Interface

MIDI interface for the Coleco ADAM, connecting via the side expansion port (60-pin card edge). Provides four 5-pin DIN MIDI jacks for connecting external MIDI instruments, synthesizers, and sequencers. The package comes complete with the interface, two MIDI cables, one 60-conductor ribbon cable to connect to ADAM, two software programs on digital data pack, and three instruction manuals.

Key ICs (verified from board photography):

INS8251N (National Semiconductor, 28-pin DIP) — Programmable Communication Interface (USART). Handles serial communication at MIDI's non-standard 31,250 baud rate. The 8251's programmable baud rate generator makes it well-suited for the MIDI spec.

MC74HC138 (Motorola, ×2) — Two 3-to-8 line decoders (HC = high-speed CMOS). Dual decoders provide individual I/O port addressing for the four MIDI ports.

DM74LS04N (National Semiconductor) — Hex inverter for signal conditioning and control logic.

Additional 74-series TTL for address decode qualification.

Architecture: The ADAM's Z80 communicates with the INS8251N USART through decoded I/O ports. The USART serializes/deserializes MIDI messages at 31,250 baud. Four 5-pin DIN connectors provide standard MIDI IN, MIDI OUT, MIDI THRU, and a fourth port. A crystal oscillator provides the MIDI baud rate reference. The MIDI IN port includes optocoupled isolation per the MIDI electrical specification. Single-sided PCB with card edge connector for the ADAM side expansion port.

Software: Shipped with SEQuel sequencer software (versions 1.0 and 2.0) and VT_Player by Bonafide Systems.