Vintage Casio Programmable Calculators

Casio, the Japanese manufacturer of mass-market consumer electronics, once had a “golden era” in which its BASIC programmable calculators were highly sought after by students and engineers around the world. Although today several companies make much more advanced calculators than the “FX” and “PB” models of years ago, these old models have that “vintage flavor” we love so much.

There are computers that have marked an era. Cars that have become the model to imitate by other manufacturers. Buildings that have established a style that other architects seek to imitate. In the world of programmable calculators, Casio models possess that special, hard-to-define touch that undoubtedly turns an object into something that transcends its mere utility.

The Casio FX-702P: A Pioneer

The Casio FX-702P, launched in 1981, was one of the first BASIC programmable models the company put on the market. Recall that at that time home computers were all the rage, and everyone seemed to be learning to program in some dialect of BASIC. Casio had the great idea of combining the renowned technology of its scientific calculators with a BASIC interpreter. The result was much better than expected. The Casio FX-702P, measuring 17 mm x 16 mm 5 x 82 mm, has a numeric keypad that also contains the common arithmetic operations, and an alphanumeric one that includes some keys for creating and editing BASIC programs. One particularity of this first model is that the alphanumeric keyboard is arranged alphabetically, making it quite cumbersome - at least at first - to try to type anything with it.

Fortunately, as was the case with Sinclair computers, it is possible to write BASIC commands by pressing just a couple of keys, because if you pay attention, you can see next to each letter - in red and blue - words that are invoked by previously pressing the “F1” or “F2” keys. Anyway, later models modified that scheme and although the possibility of entering commands “Sinclair-style” was maintained, the keys have the usual “qwerty” layout.

The screen is monochrome LCD and consists of a single line of 20 characters. The characters are formed from a 7x5 dot matrix, and are very legible. The user can write up to 10 programs (P0 to P9) and 226 variables, as long as they fit in the 1680 bytes of RAM available, almost double that of the best-selling computer of that time: the ZX81. The BASIC instructions include, as expected, a whole series of advanced scientific functions, such as hyperbolic functions, two-variable statistics, deviation and linear regression, etc. Here is an example of a program in “Casio BASIC” for the Casio FX-702P:

10 INP "X",X 20 G=1 30 S=SGN X 40 Z=ABS X 50 IF Z>9 THEN 90 60 G=G*Z 70 Z=Z+1 80 GOTO 50 90 G=LN (Z*SQR (Z*HSN (1/Z)+1/810/Z^6))*Z-Z+LN (2*/Z)/2-LN G 100 IF S>0 THEN 120 110 G=LN (-PI/X/SIN (PI*X))-G 120 PRT G,EXP G

Like the models that succeeded it, the FX-702P has the ability to connect to an FA-2 adapter to record programs on cassette tapes or print results or programs through a small printer. Its three CR-2032 lithium batteries provide about 240 hours of use.

The PB Series: More Power for More Users

The logical next step was, of course, to add memory and functions to this series of calculators. Casio began to call them “Personal Computer” with the appearance of the “PB” series around 1982, although technically they did not differ much from the “FX” models. The smallest model of the series, the PB-100, was actually somewhat more limited than the “old” FX-702P. It had 1 KB of RAM, although only 544 bytes could be devoted to BASIC programs. An expansion slot allowed this figure to be doubled, and the screen only showed 12 monochrome characters. It may seem strange that this machine has less capacity than its predecessor, but there were powerful reasons for that: to lower the price of the product. Indeed, building a PB-100 cost much less than manufacturing an FX-702P, which allowed Casio to expand the number of potential customers.

Those who wanted more power could buy, for example, the PB-700. Put on sale in 1983, it was the first machine of this type to incorporate a graphic screen capable of showing 4 lines of 20 characters or 160 x 32 pixels in graphics mode. It was powered by 4 AA batteries, measured a respectable 200 mm x 88 mm x 23 mm and weighed 315 grams. It had 4KB of RAM, of which 2.7KB could be used by the user to write their BASIC programs. A cover on the back hid three memory expansion slots, each capable of providing an additional 4KB of RAM. If all three were completed, the total memory of the PB-700 reached the possible maximum: 16KB.

At the time it went on sale, it cost almost 600 euros. Ten times more than the PB-100, although its features were worth it. Casio put many more models of this series on sale, such as the PB-1000, with “lid”, or the PB-2000, a true monster with 32KB of RAM and programmable in C. But these first models marked an era, and nothing can change that.