[Etherboot-developers] boot1a.s hacked to take .z?img directly

[<ke...@us...>]

I've hacked boot1a.s so that it can be prepended to .z?img's instead of
.z?rom's. It also takes the block count from the word at location 2 of
the boot block, which is written into by the build script,
util/builddsk.pl (new file). As a bonus, it only loads as many blocks as
needed, not the next standard size of EPROM.

It boots a single NIC driver, but when given etherboot.zimg, it fails
with a Rd err. It was trying to read 0x9B blocks. I don't know if this
is a media error, or a limitation of the packet interrupt that boot1a.s
calls.

Anyway that's one win and one not won yet. It could be that for large
drivers, the reliable method is to go through a proper loader like LILO,
GRUB or SYSLINUX.

Stuff in CVS. Testers appreciated.