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Commodore 64 keyboard functions.htm
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Commodore 64 keyboard functions.htm
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML LANG="EN">
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1">
<TITLE>Commodore 64 keyboard functions</TITLE>
</HEAD>
<BODY>
<CENTER>
<H2>Commodore 64 keyboard functions</H2>
</CENTER>
<TABLE ALIGN="LEFT" BORDER=1 WIDTH="100%">
<TR ALIGN="CENTER" VALIGN="MIDDLE"><TH WIDTH="15%"><B>Address</B><TH WIDTH="85%">Function
<TR VALIGN=TOP><TD WIDTH="15%">$E5B4<TD WIDTH="85%"><P ALIGN="JUSTIFY">Read byte from
keyboard buffer; shift keyboard buffer; decrease buffer pointer.<BR>
Input: –<BR>
Output: A = Byte read.<BR>
Used registers: A, X, Y.</P>
<TR VALIGN=TOP><TD>$EA87<TD><P ALIGN="JUSTIFY">Query keyboard; put current matrix code
into memory address $00CB, current status of shift keys into memory address
$028D and PETSCII code into keyboard buffer; handle Commodore-Shift; repeat
keys.<BR>
Input: –<BR>
Output: –<BR>
Used registers: A, X, Y.</P>
<TR VALIGN=TOP><TD>$F142<TD><P ALIGN="JUSTIFY">Read byte from keyboard buffer; shift
keyboard buffer; decrease buffer pointer.<BR>
Input: –<BR>
Output: A = Byte read; 0 = No key press available.<BR>
Used registers: A, X, Y.</P>
<TR VALIGN=TOP><TD>$F6BC<TD><P ALIGN="JUSTIFY">Update Stop key indicator, at memory
address $0091.<BR>
Input: –<BR>
Output: –<BR>
Used registers: A, X.</P>
<TR VALIGN=TOP><TD>$F6ED<TD><P ALIGN="JUSTIFY">Query Stop key indicator, at memory
address $0091; if pressed, call CLRCHN and clear keyboard buffer.<BR>
Input: –<BR>
Output: Zero: 0 = Not pressed, 1 = Pressed; Carry: 1 = Pressed.<BR>
Used registers: A, X.</P>
<TR VALIGN=TOP><TD ALIGN="CENTER" COLSPAN=2><B>Standard KERNAL functions</B>
<TR VALIGN=TOP><TD>$FF9F<TD><P ALIGN="JUSTIFY">SCNKEY. Query keyboard; put current matrix
code into memory address $00CB, current status of shift keys into memory
address $028D and PETSCII code into keyboard buffer; handle Commodore-Shift;
repeat keys.<BR>
Input: –<BR>
Output: –<BR>
Used registers: A, X, Y.<BR>
Real address: $EA87.</P>
<TR VALIGN=TOP><TD>$FFE1<TD><P ALIGN="JUSTIFY">STOP. Query Stop key indicator, at memory
address $0091; if pressed, call CLRCHN and clear keyboard buffer.<BR>
Input: –<BR>
Output: Zero: 0 = Not pressed, 1 = Pressed; Carry: 1 = Pressed.<BR>
Used registers: A, X.<BR>
Real address: ($0328), $F6ED.</P>
</TABLE><BR CLEAR=ALL>
</BODY>
</HTML>