Category Archives: hp65

HP-65 Microcode – STO and RCL

Interestingly, all of the STO and RCL instructions in program memory goto the same microcode address. Also of interest is these instructions show the clash between “merged” keystrokes and unmerged ones: STO and RCL are merged keycodes (one step for two key presses); but not all of them are merged. (I think they ran out of available codes before they ran out of key sequences and decided to keep what they could.) As a result, you can see the behaviour of both approaches in the same instruction. Continue reading HP-65 Microcode – STO and RCL