TI 58/59 ROM modules and OP instructions

[Dieter]

(12-31-2017 02:00 PM)Dave Britten Wrote:  I might be confusing this with a different calculator, or subconsciously fabricating details entirely, but I think I remember something about the internal ROM chips being a different speed than module ROMs. Does it have something to do with that in conjunction with the use of fast mode, or am I just muttering crazy things?

If I remember correctly, TI-58/59 code in RAM always has to perform some checks and tests by the OS which are not required when the code is run from ROM. This may speed up program execution by a factor of 2, as the following quote from 52-notes Volume 3 No.12 (December 1978) suggests. Here with regard to program 06 of the Math Utilities ROM:

Quote:MU-06 is the fast sorter (V3N8p6) which orders one sequence of 99 random numbers in 9¼ minutes, but which takes 19½ minutes for the same code executed in RAM.

But I do not see in which way this may be related to the question why OP-commands obviously are not used in TI ROM modules.

Dieter