EXC/ x<>Rn for stack efficiency

[Matt Agajanian]

Yes, I saw that table when it was posted. Maybe I'm missing something in your explanation. How would [f] [x<>] n (or [x<>] n) consume more than one/two bytes? HP had room for [STO] +, -, x, / n. So. wouldn't the exchange function consume one/two bytes?

ADDENDUM

Okay, upon inspecting the HP-67 table, I think I see what you're saying.

Each instruction had to be given a one-byte hex code. After all was said and done, if I read the 67 table correctly, there are only four vacant spaces. So, there was no way to give 11 (0-9, (i) ) op codes for register exchange functionality. And, limiting exchange to four registers doesn't make sense. Right?