u/benryves

I like the way you could extend the capabilities of certain models of Casio and Sharp organisers via IC cards containing additional applications. Casio didn't seem to offer as many models with this feature, and it's been quite tricky to find any compatible cards, but I do now have Casio Power Spreadsheet which is based on the same Lucid 3-D that's on Sharp's 3 Dimensional Spreadsheet card. It turns the organiser into quite a competent little number-cruncher!

I like programmable calculators and am very happy to add this Texas Instruments Galaxy 67 to my collection, especially one in such good condition. It looks like TI were going for an HP Voyager look with the design, but the LCD surround is clear plastic with a painted surround and more often than not these are very scuffed up from rubbing against the hard case.

I tend to prefer pocket computers but have been quite impressed with the programming on this model so far, with the ability to store multiple named formulae and programs. As a quick test I wrote a rough program to compute the current phase of the moon, which is in two parts. The first calculates the astronomical Julian Date (based on this algorithm):

JD=2-ip(Y÷100)+ip(Y÷400)+ip(365.25*(Y+4716))+ip(30.6001*(M+1))+D-1524.5

The second part calculates the approximate phase of the moon, returning a value between -1 and +1 (±1 for full, 0 for new) that's positive for waxing and negative for waning:

MOON=2*fp(({JD}+5.867)÷29.53059)-1

The second program calls the first with {JD}. The logic for this calculation is elaborated upon in the same pair of programs I wrote for the Casio fx-3800P, and though it's not a particularly accurate calculation on either calculator it is at least a lot more readable on the TI!

Based on some of the stored variables and formulae on the calculator the previous owner used it for electronics, so I think my next test is to adapt a preferred resistor value program I wrote for the PC-1211. A programmable scientific calculator with conditional testing and branching is a novelty, so I might as well take advantage of the situation.

Edit: Here's the resistor value formula, where E is the E-series (3, 6, 12, 24, 48, 96 or 192) and N is the index into the series (0≤N<E). Perhaps a little cumbersome but I wanted to write it as a formula rather than a program so you can use tools like auto to fill in values for N to generate a table of values automatically.

ERES=ip(₁₀^(N÷E)*₁₀^(1+(E≥48))+.5)+(E≤24)*((24*N÷E>9)*(24*N÷E<17)-(24*N÷E≡22))+(E≡192)*(N≡185)