The Censor 932 CPU architecture has one instruction type that takes a 3-bit "index register" field, but looking at the rest of the instruction set, I can't see any instructions that read, write, or otherwise manipulate index registers.

One of the possibilities that occurred to me is that it may just be that index register 1--7 are shadowed onto general register 1--7, but I hesitate to bake that assumption in to my emulator code right now.

Edit: The Censor machine architecture started out as a Standard Radio & Telefon machine in 1967-1968. In 1971 the computer division was split off and merged into Stansaab. In 1973, Facit's terminal divison was merged in. And in 1978, it was merged into Datasaab.

  • Seams like a valid assumption - I go only an instruction table, so hard to tell. On a side note, it would be helpful to add information about a machine/manufacturer in a questions - especially when it's about an unusual beast like the Datasaab 932 – Raffzahn Oct 20 at 12:04
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    agreed, unless you have specific evidence to the contrary, assume that "index register" means "which of the normal registers is being used as an index in this instruction". It is normal in many CPU architectures for regular registers to double as index registers in this way. – Ken Gober Oct 20 at 15:05

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