Microprocessor Reference & Designers Board Documentation
A community-maintained technical resource preserving documentation for the Mitsubishi M50734SP microprocessor and the RCS Microsystems Designers Board. Includes instruction set reference, peripheral documentation, schematics, monitor program disassembly, and code examples.
The M50734SP is a member of Mitsubishi's 740-Series family of CMOS single-chip 8-bit microcomputers. Based on a 6502-derived architecture with significant enhancements, the 740 series offers an efficient instruction set with powerful bit-manipulation and multiple addressing modes.
The "SP" variant is an extended microcomputer without on-chip ROM, making it ideal for development use with external EPROM. It features on-chip UART, three timers, PWM, analogue-to-digital converter, watchdog timer, and four I/O ports.
Full Architecture →Produced by RCS Microsystems Limited (Hampton Hill, Middlesex) in 1987, the M50734 Designers Board provides a complete evaluation and development environment for the 740 family. It pairs the M50734SP with 8Kb battery-backed SRAM, 16Kb EPROM, RS-232 drivers, and a ±12V power converter on a compact 100×160 mm PCB.
The on-board monitor program provides memory examine/modify, register inspection, breakpoints, and Intel/KIM hex upload/download over RS-232 at 9600 baud.
Board Details →Full documentation for all 69 M50734SP assembler instructions, including opcode tables, addressing modes, flag effects, cycle counts, and worked examples.
Browse Instructions →A fully annotated, bit-correct disassembly of the 2Kb monitor ROM at $F800–$FFFF, including all utility routines, UART handling, hex record support, and vector table.
A searchable database of all components on the Designers Board with schematic references, part numbers, supplier stock codes, and current pricing information.
Component Database →| Date | Item | Section |
|---|---|---|
| 2025-01-01 | Site launched — processor overview, designers board, monitor disassembly | Processor |
| 2025-01-01 | Initial instruction set index with ADC, AND, ASL, BCC, BCS, BEQ, BIT pages | Instructions |
| 2025-01-01 | Component database launched with initial board BOM | Components |