[Color Computer] Re: [Coco] MC-10 joystick interface

[James Diffendaffer]

The chips closest to the connector are 74LS138N's.
That's a 1 of 8 decoder/demultiplexer.
http://ece-www.colorado.edu/~mcclurel/sn74ls138rev5.pdf
Those do the address decoding.

The HEF40097BF is a "3-state hex non-inverting buffer".
http://www.datasheetcatalog.com/datasheets_pdf/H/E/F/4/HEF40097BF.shtml
This provides the connection between the joystick and the data buss.

The decoder sends out an enable for the buffer to output the lines
passed through the joystick when it's address is accessed.

The caps are for noise reduction and the resistors probably keep the
inputs to the HEF chip low till the joystick is moved or a butten is
pressed and then those lines on the HEF go high.

It should be easy to reproduce.





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