===== SilverSurfer hardware defines =====
<code>
rs16550base             = $de08

fifo_rxd     = rs16550base+$00 ;8  (r)
fifo_txd     = rs16550base+$00 ;8 (w)

fifo_dll     = rs16550base+$00 ;8 (r/w)
fifo_dlm     = rs16550base+$01 ;9 (r/w)

fifo_ier     = rs16550base+$01 ;9

fifo_fcr     = rs16550base+$02 ;a (w)
fifo_iir     = rs16550base+$02 ;a (r)
fifo_lcr     = rs16550base+$03 ;b
fifo_mcr     = rs16550base+$04 ;c
fifo_lsr     = rs16550base+$05 ;d
fifo_msr     = rs16550base+$06 ;e (r)
fifo_scratch = rs16550base+$07 ;f (r/w)
</code>