HP-25 Two Variable Statistics

[Matt Agajanian]

Hi all. Am I missing something?

After I enter x, y data pairs, when I press the mean or standard deviation button, I only see the calculation for the x values. Is there something I’m supposed to do to calculate those for y values?

Also, R0, R1, R2, and R7 were available. So, since I could enter x, y data pairs, why wasn’t the calculation for Σ(y^2) in one of the spare registers?

Thanks.

[Steve Simpkin]

As William C Wickes has said on other HP calculator projects when asked why a feature was missing from a particular model, "Life is short and ROM is full". In the case of the HP-25, this is literally true. There was no room left in the HP-25's ROM to add *any* feature unless you removed a feature or were able to further optimize the code to make more room.
https://www.hpmuseum.org/forum/thread-85...75033.html

[Matt Agajanian]

Thanks for letting me in on the details. Oddly enough, a rerun from one of my earlier posts.

Thanks anyhow!

Although…

Is it correct to presume that when the 19/29 came about, HP had the technology to be able to incorporate several high level features--now two-variable state, indirect addressing, 98 program steps, 30 registers, three subroutine levels, labels, etc.? I presume when the 19/29 were developed, the technology was able to create such higher functionality in their calculators.

[Steve Simpkin]

(09-05-2022 04:18 AM)Matt Agajanian Wrote:  ...
Is it correct to presume that when the 19/29 came about, HP had the technology to be able to incorporate several high level features--now two-variable state, indirect addressing, 98 program steps, 30 registers, three subroutine levels, labels, etc.? I presume when the 19/29 were developed, the technology was able to create such higher functionality in their calculators.

All of the features you mentioned (more or less) were present in one or more of the HP-65, HP-55 or HP-67 programmable models which were introduced before the HP-29C/19C so the technology for those features did exist previously at HP.
https://www.hpmuseum.org/cgi-bin/compare...ne&diff=ON