[Coco] Indexed addressing postbyte
robert.gault at worldnet.att.net
Sun Aug 8 21:24:29 EDT 2004
David Gacke wrote:
> Hi All,
> Could someone explain to me how the postbyte for indexed addressing
> breaks down.
> The book I have isn't clear (to me) on how to determine what it's
> supposed to do.
> Thanks very much,
> Dave Gacke
There are about 26 possible postbytes so I don't intend to list all of
them. Here is are some typical examples.
opcode D,R where R=X,Y,U or S
1RR01011 X=00 Y=01 U=10 S=11
1XX01101 16 bit offset XX=don't care
Note that bits 5&6 determine the register and the other bits determine
the function. There may be other bytes after the postbyte as needed for
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