In PDP-11 terms, the Datapoint 2200 only had these "address modes" ( https://en.wikipedia.org/wiki/PDP-11_architecture#General_register_addressing_modes https:/

In PDP-11 terms, the Datapoint 2200 only had these "address modes" ( https://en.wikipedia.org/wiki/PDP-11_architecture#General_register_addressing_modes https://en.wikipedia.org/wiki/PDP-11_architecture#General_re... ): - register - register deferred via HL - autoincrement via PC (immediate operands) No registers other than HL and PC could be output to the address bus at all. The 8080 was much more flexible, but the instructions it added weren't orthogonal, so I would say it's not at all comparable to the PDP-11 addressing modes.