history of the 4-level stack

[axd1967]

(09-06-2014 06:08 AM)walter b Wrote:  

(09-05-2014 09:11 PM)axd1967 Wrote:  I can't recall exactly where someone wrote that T was related to trig calculations.

Remember you're in a museum. Visiting another room beyond its cafeteria, you'd have found this:



(also exposed in other languages).

d:-)

Thx; so what could be the nature of the interaction between trig ops and T? Maybe trig ops involve polynomials, for which the T-drop down is handy? But wouldn't 3 levels also accomplish this?

Edit added: Classic Series Technology says "The final register did double duty as the topmost register in the stack (T) and as a working register for trigonometric functions. Thus when a trig function was used, the topmost value in the stack was lost.".