Trying to boot from CD on an 164lx.

Wrote ftp://ftp.netbsd.org/pub/NetBSD/iso/2.0/alphacd.iso
to a CD-RW using cdrecord, read the data back, compared
the bits,  and checked the md5 checksum against the md5
from ftp://ftp.netbsd.org/pub/NetBSD/iso/2.0/MD5.
I can mount the CD.

But it will not boot:

	(boot dqb0.0.1.11.0 -file netbsd -flags A)
	block 0 of dqb0.0.1.11.0 is a valid boot block
	reading 172 blocks from dqb0.0.1.11.0
	failed to read dqb0.0.1.11.0
	bootstrap failure

A Redhat Linux iso gives the same results.
A FreeBSD iso says that block 0 isn't a valid boot block.

I don't see any magic step in http://www.netbsd.org/Documentation/bootcd.html
that I have left out.

SRM doesn't say *why* it failed to read dqb...
I/O error?  File not found?  Incorrect Phase of Moon?

Any clues?