Preliminary SIMH Simulator for French CII Mitra-15 Minicomputer Under Development

Mitra-15 Simulator Initiative

A developer has initiated work on a simulator for the French CII Mitra-15 minicomputer, integrating it into the SIMH simulation framework. This early version is a tentative effort, building upon an existing SDS 940 simulator and adapting it to the Mitra-15's specific characteristics. The project relies on limited surviving documentation for the historical machine.

About the Mitra-15 Minicomputer

The Mitra-15 was a 16-bit minicomputer developed by Compagnie Internationale pour l'Informatique (CII) in the early 1970s. It was notable for its ability to program input/output peripherals using microcode, an alternative to external mechanisms like DMA. The minicomputer saw widespread use in industrial automation, scientific computing, education, and military sectors in France.

Project Goals and Progress

The simulator is intended to eventually include system and optional instructions, memory management, interrupt systems, and support for various I/O devices such as printers, disk drives, and tape readers. Current progress includes creating a working SIMH environment, developing a complete instruction decoder, and implementing code for common Mitra and CII devices, including preliminary support for DRI disks using the Mitra's suspension system.

Preserving Computing History

This simulation effort contributes to the preservation of an important part of computing history. Despite its past prevalence in France, very little software and documentation for the Mitra-15 have survived. The project addresses this scarcity by analyzing available documents and recreating the machine's functionality in a modern simulation environment.