> >>I suspect you have failed to install any boot code onto the first
> >>sector of the 'disk'.  'fdisk -c /usr/mdec/mbr sd0' will probably
> >>do it.
> >>
> >>You may want to check what is there - 'hd -C -n512 /dev/sd0d' might
> >>be illuminating.
> 
> Having run 'fdisk -c /usr/mdec/mbr sd0', the "Invalid system disk" error I 
> was seeing has been replaced by "Error No operating system". The 
> "hexdump -C -n512 /dev/sd0d" printout is attached.

and now contains the NetBSD /usr/mdec/mbr image....

Left here looking a lot better than in your mail :-)
> 0000  31 c0 8e d0 bc 00 7c 8e  c0 8e d8 89 e6 bf 00 06  |1.....|.........|
> 0010  b9 00 01 f3 a5 b9 00 02  f3 ab ea 1f 06 00 00 80  |................|
> 0020  fa 8f 7e 02 b2 80 52 52  bb 94 07 8d af 2a 00 8a  |..~...RR.....*..|
> 0030  46 04 84 c0 74 0a 80 7e  00 80 75 04 89 2e 84 0b  |F...t..~..u.....|
> 0040  83 c5 10 83 c3 09 80 fb  b8 75 e4 b0 e1 c1 e0 02  |.........u......|
> 0050  89 c6 8b b4 00 08 85 f6  75 1f b8 20 07 50 be 16  |........u.. .P..|
> 0060  07 e8 05 01 5e e8 01 01  be 1d 07 e8 fb 00 5a 31  |....^.........Z1|
> 0070  c0 cd 13 cd 18 fb f4 eb  fc 66 8b 6c 08 f6 06 91  |.........f.l....|
> 0080  07 04 75 45 5a 52 b4 08  cd 13 8b 44 02 50 c0 e8  |..uEZR.....D.P..|
> 0090  06 86 c4 c1 ea 08 42 f7  e2 8a 54 01 01 d0 83 e1  |......B...T.....|
> 00a0  3f f7 e1 5a 83 e2 3f 01  d0 48 39 e8 74 49 bb aa  |?..Z..?..H9.tI..|
> 00b0  55 b4 41 5a 52 cd 13 72  0b 81 fb 55 aa 75 05 f6  |U.AZR..r...U.u..|
> 00c0  c1 01 75 05 b8 58 07 eb  94 66 89 2e 0e 07 be 06  |..u..X...f......|
> 00d0  07 b4 42 5a 52 cd 13 b8  34 07 72 81 a0 00 7c 84  |..BZR...4.r...|.|
> 00e0  c0 74 03 a1 fe 7d 3d 55  aa b8 44 07 0f 85 6d ff  |.t...}=U..D...m.|
> 00f0  66 89 ee 5a e9 09 75 5a  8a 74 01 8b 4c 02 bb 00  |f..Z..uZ.t..L...|
> 0100  7c b8 01 02 eb ce 10 00  01 00 00 7c 00 00 00 00  ||..........|....|
> 0110  00 00 00 00 00 00 45 72  72 6f 72 20 00 0d 0a 00  |......Error ....|
> 0120  4e 6f 20 61 63 74 69 76  65 20 70 61 72 74 69 74  |No active partit|
> 0130  69 6f 6e 00 44 69 73 6b  20 72 65 61 64 20 65 72  |ion.Disk read er|
> 0140  72 6f 72 00 4e 6f 20 6f  70 65 72 61 74 69 6e 67  |ror.No operating|
> 0150  20 73 79 73 74 65 6d 00  49 6e 76 61 6c 69 64 20  | system.Invalid |
> 0160  43 48 53 20 72 65 61 64  00 60 ac b4 0e bb 01 00  |CHS read.`......|
> 0170  cd 10 ac 84 c0 75 f4 61  c3 00 00 00 00 00 00 00  |.....u.a........|
> 0180  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> 0190  1c 80 b6 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> 01a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> 01b0  00 00 00 00 00 00 00 00  e7 9d 52 95 e1 b5 80 01  |..........R.....|
> 01c0  01 00 a9 0f e0 cf 20 00  00 00 e0 9f 07 00 00 00  |...... .........|
> 01d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> *
> 01f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 55 aa  |..............U.|
> 0200

The 'No operating system' probably meany you forgot to run installboot.
Try 'installboot /dev/rsd0a /usr/mdec/bootxx_ffsv1' don't forget to copy
/usr/mdec/boot into / either.

	David

-- 
David Laight: david@l8s.co.uk