Retro Review: BA-55

[martinot]

(02-20-2018 01:41 PM)Eddie W. Shore Wrote:  The BA-55 has the [x<>y] key to:

1. Allow for bi-variate data entry: (x data [x<>y] y data [Σ+])

2. In two variable statistical analysis, pressing [x<>y] switches between standard deviation of x and standard deviation of y [σn-1]. This also applies for population deviation [ σn ].

3. The key also switch operands. This could be useful in correcting the order of the arguments in subtraction and division operations. Example: I want to calculate 78 - 26 but enter 26 - 78 by mistake:

26 [ - ] 78 (display: 78)
[x<>y] (switches the operands, display: 26)
[ = ] (result: 52, 78 - 26)

Ahh. That explains it. Thanks!

Looked very RPN-like at first.

(02-20-2018 01:41 PM)Eddie W. Shore Wrote:  Regarding the preference of y^x instead of x^y, I honestly have no idea.

Private guess and speculation; I wonder if they looked at HP calculators, and their buttons (it makes sense as a post-pix calculator, but not as in-fix), but not thinking too much about it?

I note that on newer TI calculator it is correctly (to be algebraic calculator) renamed to [x^y].

Trivia question: I wonder when (year? calculator model) TI changed their mind and went from printing [y^x] to [x^y] on the power key?

(02-19-2018 09:39 PM)Gene Wrote:  One other thing. The BA-55 can use the PC-200 printer originally aimed at the TI-66.

If you have a BA-55 where the keys work (as Eddie seems to have) you are very lucky!

Interesting! Never seen one IRL.

The P200 printer, is that TI's answer to HP's 82240A/B (or perhaps vice versa if TI was first)?

Is the printing technology about the same?

Does it connect over IR, or some serial interface?