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Re: detect character at HTAB, VTAB ( a SCRN(x,y) function for text screen) ??

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From	Jerry <awanderin@yahoo.ca>
Newsgroups	comp.sys.apple2.programmer
Subject	Re: detect character at HTAB, VTAB ( a SCRN(x,y) function for text screen) ??
Date	Fri, 29 Jun 2012 21:49:21 -0600
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aiiadict@gmail.com writes:

> I didn't know what search terms to type in.
>
> I'd like an all applesoft (I have 6502 code) program
> that will output the ascii value of the character stored
> in 40 column mode X,Y position.
>
>
> 10 vtab 10:htab 20:print "X";
> 20 y=10:x=20:gosub 1000:rem get char value
> 30 print asc(g)
>
> X
>
>
> 1000 rem use X and Y to determine ascii value, and
> 1010 rem return in variable G


You kind of had the answer in your question title:

G = SCRN( X-1, (Y-1)*2 ) + 16 * SCRN( X-1, (Y-1)*2 + 1)

HTAB and VTAB start counting at 1 whereas the LoRES stuff starts
counting at 0, hence the "- 1" terms above.

-- 
--
Jerry    awanderin at yahoo dot ca

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Thread

detect character at HTAB, VTAB  ( a SCRN(x,y) function for text screen)  ?? aiiadict@gmail.com - 2012-06-29 16:04 -0700
  Re: detect character at HTAB, VTAB  ( a SCRN(x,y) function for text screen)  ?? Jerry <awanderin@yahoo.ca> - 2012-06-29 21:49 -0600
    Re: detect character at HTAB, VTAB  ( a SCRN(x,y) function for text screen)  ?? aiiadict@gmail.com - 2012-06-30 12:06 -0700

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