Useless challenge No. 2


No. 1 is in the thread somewhere below. I remember this one that I have read somewhere decades ago:

Write a program which if number "1" is in the display (X register) would turn it into "2", and if the number "2" is there it will turn it into "1", in as few as possible steps, without using numeric, EEX or CHS keys.

There was a solution in 3 steps, say:

LBL A: ... : ... : ... : RTN


Well, I don't know if this the one you thought, but here is mine (and with a 12C !)

g e^x
g INTG (or INT)

3 steps...


Obviously you are right. If I knew the answer, it would not be a challenge:)


How about




Without any numeric !!!!!!!!!!!!!!!!!!!!!!!!!!


Without numeric of course, otherwise the obvious solution is:
3 x<>y -
2 x<>y /


Oops. Must read closer!


For the HP41, how about : LBL A : 1/X : ST+ X : RTN
That's only 2 more instructions


Hey, Tony;

you do SW as well! Good knowing. So far, you have shown as a great knowledge over HW affair. Now you come with a brilliant SW solution.


(How come your post appear two times in the same thread as being only one? I select one and both become selected... Wizard's stuff!)


To be honest, I had seen it (or a very closely related challenge) before. But I solved it then (after thinking about it for a few hours), so I think it was fair to post that solution. I wasn't copying somebody else's solution, I was copying my own :-)
And no, I am _not_ a programmer. I am much more of a hardware hacker type...


Anyway, Tony, a real beautiful solution indeed! Thanks for that little masterpiece!


While I liked the CrossTalk XVI introduction lemma, which said: "Beware of programmers who carry screwdrivers", Tony showed again that many times a HW person bring clever and elegant solutions on the SW field! Congratulations, Tony!

Andrés (being an EE, I appreciate HW too!)

Notes: CrossTalk XVI was a communications program, terminal emulator, etc for the IBM PC in 1985. HW, SW: Hardware, Software.

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