The HP-33E/C that could have been.

[Matt Agajanian]

(01-07-2023 09:19 AM)Kostas Kritsilas Wrote:  Going strictly from memory of those days, I believe that the contemporary calculator for the HP-25/25C was the TI-58/58C. and the TI-58/58C had 480 partially merged program steps, maximum (I seem to recall that you could re-allocate program steps to registers). The HP-67 (224 fully merged steps) equivalent was the TI-59 (960 partially merged steps). The later HP-29C had 98 or 100 fully merged steps, and a bunch of added programming features over the HP-25/25C like indirect addressing and subroutines, some of which were in the TI-58/58C already.

The earlier generation programmables were the HP-55 (49 un-merged steps) and HP-65 (100 un-merged(?) steps) vs. the SR-56 (100 un-merged steps) and SR-52 (I don't remember how many steps it had). I also don't recall the register counts for each.

The SR-52 had 20 registers with 224 partially merged program steps. Only the operations which needed the 2nd key were merged. For example 2nd if zero. Memory and branching locations weren't not merged. For example, GTO 145 took four program steps- GTO 1 4 5.

The SR-56 had the same characteristics. Memory was 10 registers with 100 program steps. 2nd functions were merged, but not the memory nor transfer addresses.