I have found a inconsistency (by reading, since I don't have a working kernel 
for my Duo230) in the file machdep.c (current 16.4.97)

I think the romvectors for the Powerbook Duo 270C, 280 and 280C are wrong.

Line numbers 1899-1901 

	{MACH_MACPB270, "PowerBook Duo", " 270C ", MACH_CLASSDUO, &romvecs[5]},
	{MACH_MACPB280, "PowerBook Duo", " 280 ", MACH_CLASSDUO, &romvecs[5]},
	{MACH_MACPB280C, "PowerBook Duo", " 280C ", MACH_CLASSDUO, &romvecs[5]},

should be 

	{MACH_MACPB270, "PowerBook Duo", " 270C ", MACH_CLASSDUO, &romvecs[10]},
	{MACH_MACPB280, "PowerBook Duo", " 280 ", MACH_CLASSDUO, &romvecs[8]},
	{MACH_MACPB280C, "PowerBook Duo", " 280C ", MACH_CLASSDUO, &romvecs[8]},


And could you please add the following entries for the Duos to the 
"intvid_info[]" (line number 1929).

	{MACH_MACPB210,		(caddr_t) 0x60000000,	128 * 1024},
	{MACH_MACPB230,		(caddr_t) 0x60000000,	128 * 1024},

I don't know the exact video-base-address of the 250, 270 and 280, but I guess 
it's the same as above. Vram-size of the 270 and 280 is 512kB.

	{MACH_MACPB250,		(caddr_t) 0x60000000,	128 * 1024},
	{MACH_MACPB270,		(caddr_t) 0x60000000,	512 * 1024},
	{MACH_MACPB280,		(caddr_t) 0x60000000,	512 * 1024},
	{MACH_MACPB280C,	(caddr_t) 0x60000000,	512 * 1024},



I hope I'll get access to a macbsd-capable machine in the near future to 
compile a custom kernel for my Duo 230.

Thanks, Thomas Walter