GM P4 $400x regs

[Mike]

The control registers of the P4-chipset which are mapped to $400x in all P4s
I've seen...From some work I'm doing on several PROMs concurrently, I see
that $4009 is the serial receive register, $400A is the serial transmit
register and $4007 is the SCCR2 (HC11 $102D) equivalent. $4008 appears to be
the "SCI" status register.

$4008 appears pretty close to bit-for-bit compatible with the standard HC11
$102E SCSR register except bit 0. Anyone know what this bit is doing?

--
Mike

-----
 Mike