hardware questions

[Dan Olson <dano@agora.rdrop.com>]

I hope people on the list don't mind some hardware questions, especially
with things being perty quiet the last few days.  I will definetly be
using this hardware to run ELKS, btw, so it shouldn't be too far off
topic.

I've had the idea of building a PC clone from scratch for some time now,
and I think I'm finally going to try it.  Unfortunatly I haven't yet found
any good documentation on the inner working of the PC or 8088 CPU.  As
far as I can tell, the machine is fairly simple, so hopefully this won't
be too much of a project.  I'm thinking of using an ISA backplane and
building everything as ISA card modules, to make things a little easier.
I'm going to start with a RAM card, using static ram (or maybe just using
a modified aftermarket card if I find one).  Because the 8088 is a 16 bit
CPU with an 8 bit data bus, I am not totally sure how memory is
read/written.  I assume that because the word size is 8 bit and because
all 20 address lines are available on the bus, that the CPU just addresses
the word it wants and the memory card functions just as if it were hooked
to an 8 bit CPU.  I'm also wondering if I can take a functioning XT,
remove the 4164 or 41256 RAM chips, and replace them with my ISA card and
still have the machine work.  If the on-board memory is gone, would
anything else try to drive the bus?  Finally, any pointers to any good web
pages or other sources of info would be great.  Thanks.

	Dan