INPUT stack lift: 32S vs. 42S

[Thomas Okken]

(10-11-2019 02:01 PM)rprosperi Wrote:  I think the 32S implements what most would consider the 'right way' to behave, if unhindered with legacy behavior, while the 42S, positioned as the 41C successor and ostensibly compatible with existing 41C code, did not have the freedom to behave logically. There are other similar issues where the 42S leans back towards 41C behavior while the 32S/32SII/33S/35S, etc. lean towards more evolved thinking.

When it comes to the behavior of INPUT on the 42S, 41C compatibility was not a concern, though, since that function does not exist in the 41C (nor in the X Functions module, from which the 42S borrowed a few functions as well). And the 42S designers were not afraid to deviate from 41C conventions when it made sense, most noticeably in the behavior of COMPLEX, where you enter <re> ENTER <im> COMPLEX, while the behavior of Σ+ might lead you to expect that you'd have to enter <im> ENTER <re> COMPLEX.

I think the behavior of INPUT makes sense in its own right, because it makes it easy to modify the existing value of the variable; getting pushed into Y means you can perform calculations on the original value without any preliminaries.