HP28S screen noise generator

[Keith Midson]

Hi all, following on from THIS thread, here is the HP28S program that produces a hypnotising screen display:

<< IMG 'TEST' STO 1 738 START

TEST 548 548 SUB TEST 1 547 SUB +

TEST XOR 'TEST' STO TEST ->LCD NEXT >>


You need to store a screen dump into the file 'IMG' first. Have fun! Will look like THIS , but the moving image is much more impressive than you can do justice with in a still picture. Cheers, Keith

[Gerson W. Barbosa]

Great for "I'd gladly lend it to you, but it's gone wacky!"

[Namir]

Keith,

Stop abusing these poor machines!!!!

:-)

Namir

[Keith Midson]

they love it! ;-)

[Cristian Arezzini]

Thank you Keith! :)

Cristian

[C.Ret]

Many Thanks for remember me bitmap screen plays on my old HP-28S.

If my memory don't abuse me, this code may not run on HP-28C due to the use of the XOR on strings. XOR function may not handel binary or screen strings on HP28C; only integers and regular binaries.

In your code, I still not understand why you loop 738 times ? Is there samething I miss interpret, is ther any effect I miss ?

«

  IMG 'TEST' STO

  1 738 START

           TEST 548 548 SUB

           TEST   1 547 SUB +

           TEST XOR

          'TEST' STO

           TEST ->LCD

  NEXT

»

(what a bunch as TEST ?)

Please consider my translation of your code without any use of any global variable. My version directly use actual screen apparence and loops until one key is pressed.

«

  DO

     LCD->

     DUP  548 548 SUB

     OVER   1 547 SUB + XOR

     ->LCD

  UNTIL

     KEY

  END

  CLMF

»

Great effet HP28S feature, isn't it ?

May same one bring down a version for HP48/49/50 ?

Edited: 19 Feb 2012, 4:10 a.m.

[Keith Midson]

That is a much better version of the program - thank you! I have long lost my original code from 1990, which was much neater - I wrote this in a hurry to see if I could replicate the effect all these years later.

I think I used the word 'test' as it was me 'testing' to see if I could get it to work (after not using RPL for more than a decade). As for the importance of 738 ... I have no idea!!

I would love to see a comparable program on the 48 - when I upgraded to the 48 I was very disappointed that the screen graphics were handled so differently (and never actually took the time to learn).

[Gilles Carpentier]

"May same one bring down a version for HP48/49/50 ?"

Hello C.Ret... I don't understand the prog HP28 here... On the 48/50 bitmaps are special object and not strings...

Some ideas on 50G :

«

  DO

    LCD-> DUP {#0 #4} {#130 #79} SUB {#0 #0} SWAP GXOR ->LCD

  UNTIL

     KEY

  END

»

or

«

  DO 

    LCD-> NEG ->LCD

  UNTIL

     KEY

  END

»