FWIW, the CDC 6600 and Cray instruction set architectures also had this address vs. data distinction in their (scalar) register files. Both could do basic integer operations, but only the address registers could be used for address calculations in load/store instructions, while only the data registers could do floating-point.
(Strictly speaking, the CDC 6600 didn't have load/store instructions per se. Instead, any time you modified address registers A1-A5, a load to the corresponding data register X1-X5 took place from the resulting address. Modifications to A6-A7 caused a store from X6-X7 to the resulting address. It made for such tight code!)
(Strictly speaking, the CDC 6600 didn't have load/store instructions per se. Instead, any time you modified address registers A1-A5, a load to the corresponding data register X1-X5 took place from the resulting address. Modifications to A6-A7 caused a store from X6-X7 to the resulting address. It made for such tight code!)