TI 58/59 ROM modules and OP instructions

[rprosperi]

(12-30-2017 03:34 PM)Gene Wrote:  As another guess, sometimes factory software has to be written very early in the development life of the calculator (which is one reason it is so often so bad!)... perhaps the development finalization of the OP code structures wasn't early enough to be reliably used in the library modules?

I hadn't thought of this but it makes sense. To keep the mfg. cost of the ROM modules low, TI would have used true ROM (vs. OTP, EEPROM or EPROM) which had a lead time of many weeks to months, so it's possible that in order to have them available to ship simultaneously with the machines (some even in the box) they were created using core programming language commands, while the OP commands were being completed/tested in parallel. This was exactly the case with some of the Wizard products even 10 years later.

If anyone knows which ROM modules were released well after product launch, it may be revealing to see if these late ROMs used the OP commands in their code.