POLLKEYB  -  AT-KEYBOARD PORT READER
------------------------------------


  This code is to read numeric scancodes from an AT-keyboard or from a 
barcode reader, which uses this port.

Usage:

       sys49152,a%

   eg: 10 b%=0
       20 a%=b%:sys49152,b%
       30 ifa%=240andb%=22then print"key 1 is pressed and released"
       40 ifa%=240andb%=30then print"key 2 is pressed and released"
       50 goto 20

 This call is blocked until it can read a byte from the AT-keyboard port.
Pressing stop key aborts blocking without error, and this does not alter
the previous variable's (a%) value.
 Also note that given variables must be integer type.

Alternate Usage:

       10 sys49155:if(peek(783)and1)=1goto 10
       20 a%=peek(780)
       30 print a%

   or;

       10 sys49155:ifpeek(780)=0 goto 10
       20 if(peek(783)and1)=0thena%=peek(780)
       30 print a%
       20 rem at-keyboard does not send a $00 value.


 You can find other information about the AT-keyboard interface at:
http://www.physics.metu.edu.tr/~filker/cbm.html


1998-Jan-21

Ilker Ficicilar
filker@newton.physics.metu.edu.tr

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