Spacelab’s Mitra 125 MS
The article discusses the Mitra 125 MS, a French-built minicomputer used in Spacelab during the 1980s. It highlights the computer's architecture, which relies on a series of cards rather than a microprocessor, and its military-grade ALU. The Mitra 125 MS was eventually replaced by the IBM AP-101SL in 1991 as technology advanced.
- ▪The Mitra 125 MS was a minicomputer used in Spacelab, a European lab designed for the Space Shuttle.
- ▪It operated without a microprocessor, utilizing a series of cards and a military-grade ALU for calculations.
- ▪By 1991, the Mitra 125 MS was considered obsolete and was replaced by the IBM AP-101SL.
Opening excerpt (first ~120 words) tap to expand
Spacelab’s Mitra 125 MS No comments by: Al Williams May 24, 2026 Title: Copy Short Link: Copy [Ken Shirriff] does some of the most interesting teardowns. This time, he’s looking at a French-built minicomputer called the Mitra 125 MS from around 1980. In particular, it was the computer inside Spacelab, a European lab that could fit in the back of the Space Shuttle. As you might expect, the computer doesn’t contain a microprocessor. Instead, it is a series of cards and, in this post, [Ken’s] looking at the ALU that allows the computer to perform math operations. The Mitra was a descendant of a 1971 computer, and the “MS” indicated it was a military-grade variant of the computer. Spacelab had three of these. One operated the lab, another handled experiments, and the third was a backup.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at Hackaday.
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