Hello David!

  DL> 512 would be luxury!  Remove 4x16 for the partition table and 2
    > for the 55, aa at the end, the bootsel setup steals 9x4 (names),
    > another 55aa, two bytes timeout, flags and default key.  So 512
    > - 2 - 62 - 2 - 36 - 4 = 404 bytes for the code and messages.

Who says there are no challenges in software development any more? ;-)

  DL> fdisk normally reports two sets of values (from my disk):

I don't believe it did on the machines I've installed on most recently
(both 486 based Compaq ProLinea).

  DL> No - there is a second piece of code that sysinst will put into
    > the mbr.  

Perhaps I should have said "boot sectors".

[Boot Selector]

  AB> Possibly also useful if I want to test different kernels and
    > boot devices?

  DL> Boot devices in the sense that it will read the mbr from a
    > different disk, different kernels only if they are in different
    > partitions.

So, that part after the colon always has to be "netbsd" (e.g. boot
sd0a:netbsd) ?

  DL> A second system!  I'm testing the mbr a single system.....  

The second system did not exhibit the same symptoms.  Since it has a
different (smaller) disk, this may lend some weight to the suggestion
that it may have been geometry related.

I've mostly done what I wanted to with the first ProLinea, so I'll try
wiping the disk, writing another diagnostic partition, and installing
NetBSD in an attempt to reproduce its earlier behavior.

- Andy Ball.