jurjen@cwi.nl (Jurjen NE Bos) (03/26/91)
(This is posted for my brother-in-law Eric Toonen.) Introduction ============ Believe me, this is one of the better things one can do with a calculator. As a joke, I received a calculator, named the "Puzzo Cal". It is a six-function calculator, with a special keyboard. The keyboard has removable keys. The keys are: +----+----+----+ | | | | <-- Three yellow keys and an unused space | OFF| % |sqrt| +----+----+----+----+ | | | | | <-- Four green keys | 7 | 8 | 9 | / | +----+----+----+----+ | | | | | <-- Four blue keys | 4 | 5 | 6 | x | +----+----+----+----+ | | | | | <-- Four orange keys | 1 | 2 | 3 | - | +----+----+----+----+ | | |CE/ | | <-- Four red keys | 0 | . | ON| +/=| +----+----+----+----+ Note: The keyboard shown on the box has different colors. Also, the key "CE/ON" is labeled "ON/C" on the box. The keys are an exact square. When you change a key's location, the key's function moves with it. This is what the "Puzzo Cal" is all about. (There is no other name or country of origin on the box or the calculator). Function programmed in pins =========================== When I took a look at the back of the keys, I figured how this (the moving of the keys) was done. The function was programmed in several pins. There are twelve places where such a pin could be: +--O--O--+ | | O O O O | | O O O O | | +--O--O--+ I named the pins: +--B1-C1-+ | | A2 B2 C2 D2 | | A3 B3 C3 D3 | | +--B4-C4-+ And made a diagram for each function, to see what pins are with what function. Every key has exactly two pins, and there is never a pin C4. After sorting the diagram it looks like this: Key-cap: B4 B3 C3 C2 D2 D3 A3 A2 C1 B2 B1 Function: ----------------------------------------------------------------- sqrt X X sqrt 0 X X 0 1 X X 1 2 X X 2 3 X X 3 . X X . 4 X X 4 5 X X 5 6 X X 6 7 X X 7 8 X X 8 9 X X 9 - X X - % X X % +/= X X + / X X / * X X * CE/ON X X ON OFF X X OFF ---------------------------------------------------------------- As you can see, there are several unused combinations. It is obvious that most combinations are invalid, there are "columns" and "rows". New functions - the easy way ============================ I made a small computer-program doing rotations with existing keys. This way, I made new combinations. WITH THESE NEW COMBINATIONS, THERE WERE NEW FUNCTIONS! Key: B4 B3 C3 C2 D2 D3 A3 A2 C1 B2 B1 Function: ----------------------------------------------------------------- 6 rotated right X X MC - rotated right X X MR 5 rotated left X X C 3 rotated left X X = sqrt upside down X X M+ 3 rotated right X X (none) 1 rotated right X X (none) ----------------------------------------------------------------- Now, we went from a calculator without memory, to a calculator WITH memory (there already was a "M" annunciator). The other D3 combinations (except ON and OFF) have no other strange behaviours. The D3-line is probably connected to an interrupt line of the processor or something. Note that I found the actual "=" key. The "+/=" key on the keyboard is the "+" function (There were too many keys, I guess). The new "=" function DOES behave as an "=". Just to be complete I will explain. x^y can be calculated by: <x> (and pressing [X] <y> times) [=] 1/x can be calculated by: <x> [/] [=] -x can be calculated by: <x> [-] [=] The [=] is auto-repeat: 4 [X] 3 [=] {12} 4 x 3 =12 5 [=] {20} " x 5 =20 5 [-] 2 [=] {3} 5 - 2 =3 4 [=] {2} 4 - " =2 All of these things can not be done with the "Puzzo Cal"s [+/=] key. Some combinations can not be made with the existing keys. At least that's what I thought at first. The combinations were: B3-A2, C2-C1 and D2-A3. I figured a way to make them anyway: Still more new functions - the hard way ======================================= B3-A2: position the "sqrt" key half on top of the key-location: +----+ | | <--+ |sqrt| | +----+ | This is the place where a key should be +----+ <--+ The function made this way is "MRC" (press once for MR, second time for MC). This is interesting, cause normally those cheap calculators have either an MRC-button or two buttons, MR and MC. This shows that both functions are available on one microprocessor. D2-A3: Position an upside-down "5" key half on top of the key-location: +----+ | 5 | <--+ | | | +----+ | This is the place where a key should be +----+ <--+ The function now made is the "M-" function. C2-C1: position the "2" and the "8" next to each other, on the middle of the key-location: +----+----+ | | | | 2 | 8 | +----+----+ ^ ^ | | +----+ This is the place where the key should be. The function now made is the "+/-" (negate) function. Conclusion ========== There is a lot people can do with al sort of handheld machines. Even the most simple calculator can be a challenge. The inventor of the Puzzo Cal probably thought of this. I think it's a great little thingie. It is a shame that the actual creator of the "Puzzo Cal" is probably not the inventor. Why else is there nowhere a company name found on it? Result table: A3 A2 C1 B2 B1 +---------------------------------------- B4 | sqrt 0 1 2 3 B3 | . [MRC] 4 5 6 C3 | [MC] 7 8 9 - C2 | [MR] % [M-] [C] + D2 | [+/-] [=] [M+] / x D3 | ON OFF +---------------------------------------- The functions in brackets are new ones, not accessable in "normal" use. ============================================================================== Eric Toonen Collector of weird calculators Djept-Zuid 6 5502 RP Veldhoven The Netherlands E-mail: toonen@hsepm1.hse.nl ==============================================================================
kenw@col.hp.com (Ken Wyatt) (03/27/91)
Maybe I shouldn't divulge any secrets, but the HP48 actually has 4000 functions. The hidden ones are accessible by flipping the keys upside down. 8-)