When I acquired my Casio fx-201P, I was under the impression that it was Casio's only early VFD programmable calculator. I've since been proven wrong more than once: it appears that at the time, Casio had an entire family of machines based on this model. One member of this family is the fx-202P, which has the same capabilities as the fx-201P, with one rather important difference: it uses CMOS memory that has a battery backup. In other words, along with HP, Texas Instruments, and Sharp, Casio also had an entry in the market of "continuous memory" programmable calculators in the mid-1970s.

Today is a bright, early spring day made brighter by the fact that the mailman brought me a wonderful gift: a real live working fx-202P! Thank you, Hugh! These rather large-ish scientific calculators somehow manage to convey a sense of magic that is so often missing from later models, no matter how capable.

The fx-201P/202P family uses a rather unusual, programming language like programming model. Highly unusual is the fact that programs are not like interactive keystroke sequences; for instance, if you wish to add 1 to memory register 0, the program would read 0 = 0 + K 1, much more like a procedural language than a keystroke macro.

Back when I first acquired an fx-201P, I explored its capabilities by writing yet another program for the Gamma function, my favorite programming example. Presented here in short form, it neatly demonstrates the calculator's capabilities:

ENT 1 :
2 = K 1 :
ST# 3 :
IF 1 = K 9 : 1 : 2 : 2 :
ST# 1 :
2 = 2 × 1 :
1 = 1 + K 1 :
GOTO 3 :
ST# 2 :
0 = K 1 ÷ K 105 ÷ 1 ÷ 1 :
0 = K 1 ÷ K 30 - 0 ÷ 1 ÷ 1 :
0 = K 1 - 0 ÷ 1 ÷ K 12 :
0 = 1 × ln - 1 + 0 - 2 ln:
2 = K 6.2831853 ÷ 1 :
0 = 2 √ ln + 0:
ANS 0 :