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From: miller@uiucdcs.UUCP (miller )
Newsgroups: net.micro.cbm
Subject: new io ports for c64 - (nf)
Message-ID: <4845@uiucdcs.UUCP>
Date: Tue, 10-Jan-84 22:26:56 EST
Article-I.D.: uiucdcs.4845
Posted: Tue Jan 10 22:26:56 1984
Date-Received: Sun, 15-Jan-84 00:43:05 EST
Lines: 14

#N:uiucdcs:36100026:000:607
uiucdcs!miller    Jan 10 16:41:00 1984


I am trying to add new I/O ports onto my c64 through the expansion port.  I
want them to look like the user port, only in a different address space.  I
tried duplicating the hardware (pull up resistors, etc.) and control lines
used in CIA 2 out the back of the expansion port.  But for the chip select,
I used I/O1 or I/O2 instead of CIA2 (which should map into $DF00 or $DE00).
Unfortunately, this did not work.  I get the handshaking line out the back of
the 6526 to flip, but the output data lines stay high.  Has anyone ever added
extra I/O ports onto the c64 and can offer suggestions?

A. Ray Miller