@lp0_on_fire@social.linux.pizza
2026-02-14 18:41 UTC
@TimWardCam @ryanc, let's see… from what I remember:
8-bit registers (treatable as 16-bit pairs): A, F, B, C, D, E, H, L.
16-bit registers (treatable as 8-bit halves): IX, IY.
8-bit registers: I, R.
16-bit registers: AF', BC', DE', HL', SP, PC.
18 registers in total. I'm specifically not counting different views as distinct registers: AF is counted as A and F, but IXH and IXL are counted as IX.
Yes, some aspects of this are… somewhat arbitrary. I could count BC, DE and HL as three rather than six and it wouldn't be wrong. I could count AF that way too – and it probably does match the other pairs in terms of the actual hardware design (and it could reasonably be called FA as, looking at the opcode patterns, it makes sense for A to be the lower 8 bits).
Now. Have I missed anything…?
Replies (1)
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@TimWardCam@c.im 2026-02-14 18:43
@lp0_on_fire @ryanc Most people never come across R. I knew someone who bult a Rugby clock with no RAM, using just the registers as memory, and to find enough space they needed to use the top few bits of the R register (the bottom few bits cycled too fast to be useful).