🚀 go-pugleaf

After months of searching (and perusing the latest PC Magazine review
of 80 laptops), it has become evident that essentially no one makes a
laptop or notebook with an ISA (AT-type) card slot.  I guess the main
reasons for such slots (modems and network adapters) have been taken
care of in other ways.

Be that as it may, I'm still trying to put together a field portable
data acquisition system.  I want to use a generic A/D board, supported
by generic software, so neato-nifty parallel/serial port solutions are
out.

Most laptops and notebooks, though they don't have an ISA slot
internally, support an external expansion chassis which will take
standard boards.  These expansion units are AC powered and (I assume)
contain a power supply which generates the standard 5 V and 12 V power
on which PCs feed.

It occurs to me that it should be possible to rip out the power supply
in one of these expansion units and replace it with a battery and a
little magic circuitry to generate the needed voltages.  As you may
gather, I'm an electronics nimrod, so this seems plausible to me, but I
can't tell if it's actually feasible.

So, here are the questions:
1) Has anyone done this before?
2) What sort of batteries might be appropriate for this?
3) What magical little bits of circuitry would be needed?
4) Is this a totally impractical idea?

I'll happily summarize and post the results.