[vcf-midatlantic] 2:00am BASIC epiphany
Evan Koblentz
evan at vcfed.org
Fri Aug 31 08:43:14 EDT 2018
>> You're a Major in the English Army? Didn't strike me as the sort of chap
Her Majesty's Royal Batallion of Puns and 1980s Toys.
On Fri, Aug 31, 2018, 5:32 AM Henry S. Courbis via vcf-midatlantic <
vcf-midatlantic at lists.vcfed.org> wrote:
> >just another English major
>
> You're a Major in the English Army? Didn't strike me as the sort of chap.
>
>
>
>
> Henry S. Courbis
>
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> On Thu, Aug 30, 2018 at 11:30 PM, Evan Koblentz via vcf-midatlantic <
> vcf-midatlantic at lists.vcfed.org> wrote:
>
> > I had a spontaneous idea tonight for removing two lines of my Lego robot
> > code.
> >
> > As usual, this epiphany on my part is probably TOTALLY FRIGGIN' OBVIOUS
> to
> > most of you, but I'm proud that I figured it out on my own. :)
> >
> > Before, on the forklift robot, this was my code for checking the
> > upper/lower touch sensors (limit switches) and moving the forklift motor
> > appropriately. I had it at 9 lines (not counting REMarks) which was
> greatly
> > reduced from Dan R.'s original 16 lines.
> >
> > 3010 IF PEEK (49249) > 127 AND PEEK(L) = 64 THEN RETURN
> > 3020 IF PEEK (49249) > 127 THEN POKE L,16
> > 3030 IF PEEK(L) = 80 THEN RETURN
> > 3040 IF PEEK(49249) > 127 THEN GOTO 3020
> > 3050 IF PEEK(49250) > 127 AND PEEK(L) = 128 THEN RETURN
> > 3060 IF PEEK(49250) > 127 THEN POKE L,32
> > 3070 IF PEEK(L) = 160 THEN RETURN
> > 3080 IF PEEK(49250) > 127 THEN GOTO 3060
> > 3090 RETURN
> >
> > Background: In that code, PEEK(49249) in Applesoft checks joystick button
> > 0 and PEEK(49250) checks button 1. If their value is greater than 127
> then
> > you know they're currently being pressed. PEEK(L) checks the value at the
> > address of the interface card. 64/128 are the sensors attached to ports
> > (bits) 6 and 7, respectively. POKE L,16/32 turns on the motor (in
> opposite
> > directions) that's attached via a connector spanned to ports 4/5. Lines
> > 3030 and 3070 stop the motors if the sensors become active ** while **
> the
> > motor is moving, because then the total value being read from the
> interface
> > box is sensor + the motor.
> >
> > The idea that popped into my head tonight: you can combine lines
> 3010/3020
> > into one, and also lines 3050/3060 into one, thereby reducing the routine
> > by two lines and having the same effect.
> >
> > 3010 IF PEEK (49249) > 127 AND PEEK(L) <> 64 THEN POKE L,16
> > 3020 IF PEEK(L) = 80 THEN RETURN
> > 3030 IF PEEK(49249) > 127 THEN GOTO 3010
> > 3040 IF PEEK(49250) > 127 AND PEEK(L) <> 128 POKE L,32
> > 3050 IF PEEK(L) = 160 THEN RETURN
> > 3060 IF PEEK(49250) > 127 THEN GOTO 3040
> > 3070 RETURN
> >
> > So instead of saying, "Exit the routine if the lower/upper touch sensors
> > are active, which we know is true if the value at address L is 64 or
> 128,"
> > instead I'm saying, "Turn on the motor ** ONLY IF ** the lower/upper
> touch
> > sensors aren't active."
> >
> > I can't test it until this weekend at the soonest, but I am ** pretty
> sure
> > ** it'll work -- or at least I don't see any obvious reason why it would
> **
> > not ** work. After all, the forklift motor can't turn on when either
> sensor
> > is active, because I'm not programmatically allowing it -- right?
> >
> > If it works, then I'll convert it to IBM BASIC too. The button PEEKs
> > become STRIG (stick trigger) values, and the POKEs become OUT.
> >
> > Saving two lines of interpreted / non-compiled BASIC isn't going to have
> > any significant impact on program execution speed or disk space, but it
> > makes the code that much easier for non-programmers to understand, and it
> > gives me that much more confidence of about being than just another
> English
> > major. :)
> >
>
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