This plug-in is an extended memory device, which may be accessed through the
I/O page.  As supplied it has 8 MB of memory, with four registers starting
at location 17777100:

base+0	data port

base+2	autoincrementing data port

base+4	low address

base+6	high address

The 31-bit address (bit 0 is always 0) gives the current offset within the
8 MB buffer (starting at 0).  Word or byte accesses to the data port access
the word or byte at the current offset (odd byte accesses go to the high byte
of the word as you'd expect).  Same with the autoincrementing data port except
that the address is incremented (by two regardless of access type) after the
access.

Rebuild with:

wasm emem32
wlink @emem32

John Wilson, 19-Sep-2008