[Coco] Updated BASIC possible, was Reading keyboard input without basic

Barry Nelson barry.nelson at amobiledevice.com
Wed Feb 10 10:50:31 EST 2016

 Since this CoCo Flash cartridge I am writing software for would allow a CoCo 3 to map flash rom from $8000 to $FFFF I would be quite so sure that no one will create an updated BASIC.

> Arthur Flexser flexser at fiu.edu 
> Wed Feb 10 08:06:56 EST 2016
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> The two most basic (no pun intended) ROM routines in Color Basic for
> getting keyboard input are called by JSRs to $A1C1 or $A1B1.  In both
> cases, the character that is input from the keyboard is returned in the A
> register.  The difference between the two is that the $A1C1 routine returns
> zero until a key is pressed, so a call to that is generally embedded in a
> loop that is exited when a nonzero value is returned.  The one at $A1B1
> blinks the cursor and waits until a character is entered.  (This is from
> memory, no guarantees.)  The one at $A1C1 also has a documented vector and
> so may also be called by JSR [$A000] if memory serves me correctly.  (Or
> maybe it's $A002, too lazy to look it up.)  But there's no particular
> advantage to using that, since we now know that there will be no future
> Basic version where a direct call to the routine won't work because the
> entry point has changed.
> Art

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