Knoppix has cheat codes, which you can type at the boot prompt.
Various Linux Live CDs allow you to press function keys, while the
boot prompt is present. On Knoppix 6, you might have F2 and F3 for
example.
Each function key has a small text file bound to it, with command
options. When there are bootup problems, you can use cheat codes
to try to get the thing to start.
knoppix acpi=off nolapic
Knoppix 6 lacks a bit in terms of these details, so not everything
may be documented as well as it should. (For example, the documentation
may indicate you have a wealth of window managers to choose from, but
all that appears to be present is LXDE.) One of the earlier releases
have a pretty comprehensive list of options or cheat codes. The
initial release of 6, didn't have the cheat codes finished. More
of them appeared in 6.01.
http://www.knoppix.net/wiki/Cheat_Codes
Each release, doesn't necessarily build on the previous one. For
example, the release 6 version uses a lot more stuff you might have
seen in Debian, so it would appear to try to not diverge so much
from the core software. The previous versions had lots of colored
text messages sent to the screen, during the boot process, which
helps if the hardware is busted. You can see stuff failing when
your processor is flaky and so on. My all time favorite version
is the 5.3.1 DVD, but not many people like such a large download,
just for a maintenance tool.
HTH,
Paul