pc5.jpg (42370 bytes)The Tandy/Radio Shack PC-5 is a BASIC programmable handheld calculator. If you think you've seen it under another name, you're not mistaken: it is really a Casio model, the Casio fx-780P to be precise.

I was never too fond of folding-design calculators. True, their design protects the display and helps keep the keyboard clean. On the other hand, the design tends to be fragile, and one-handed operation is more difficult. To Casio's credit, the flexible ribbon connections between the two halves (just like the flexible ribbon connectors that are used internally, for instance with the LCD display) tend to be very reliable. If only the same thing could be said about other models, including some brand-name calculators from the likes of TI or Sharp!

The following program, computing the Gamma function to a high degree of precision, demonstrates the programming model of this calculator:

10 INPUT X
20 Z= ABSX
30 G=1
40 IF Z>9 THEN 80
50 G=G*Z
60 Z=Z+1
70 GOTO 40
80 G=( LNZ+ LN SQR(Z* HYP SIN(1/Z)+1/810/Z^6)-1)*Z-LNG
90 G=G+ LN SQR(2*π/Z)
100 IF X>0 THEN 120
110 G= LN(-π/X/ SIN(π*X))-G
120 PRINT G, EXPG