TI 58/59 ROM modules and OP instructions

[Dieter]

(12-30-2017 02:51 PM)rprosperi Wrote:  Not having used a 58/59 back in the day, I had no background on the OP commands, and guessed they are not used in programs as they are much slower than the equivalent commands used to replace them (recalling how obsessed with program speed everyone was).

It's exactly the other way round: OP 20...39 are faster than 1 (INV) SUM nn, maybe even plus two leading/trailing x<>t commands to preserve the number in the display. I just found a reference in a 52-notes issue that recommends these OP commands because of their speed and other benefits.

However...

(12-30-2017 02:51 PM)rprosperi Wrote:  Or possibly programs in ROM could not access the OP commands, due to some internal architectural limitation?

That's exactly what I think. Either it is this, or maybe the other possible explanation that assumes the ROM programs have been written before the final calculator design including the OP commands was fixed.

Dieter