Dead PET4032

[tony duell]

> Look for inconsistencies in voltages and pulses to and from RAM.  You may
> need RAM at the lowest memory locations to boot.  Hooking up the keyboard
> at least to eliminate a missing keyboard as a reason the system does not

The PET keyboard is just a matrix of switches, if nothing it pressed it tests as
an open-circuit between all pins. So the machine can't fail to start up because
the keyboard is not connected.

-tony