ELKS in space ....

ELKS in space ....

[Paul Nasrat]

Thanks to Mike for pointing me at this:

http://flightlinux.gsfc.nasa.gov/

Let's all wave at UoSat-12 then:

http://www.sstl.co.uk/missions/mn_uosat_12_extra_stat1.html

Paul

Re: ELKS in space ....

[Miguel Bolanos]

Hi all!

On Tue, 15 Oct 2002, Paul Nasrat wrote:

> Thanks to Mike for pointing me at this:
>
> http://flightlinux.gsfc.nasa.gov/

No problem :)

>
> Let's all wave at UoSat-12 then:
>
> http://www.sstl.co.uk/missions/mn_uosat_12_extra_stat1.html

Hey this looks very nice, does anyone know of similar projects on which
ELKS is been used for space related stuff?
Even anyone willing to start a new project based on ELKS?
yours

Mike

hardware questions

[Dan Olson]

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

Re: hardware questions

[jb1]

On Fri, 29 Nov 2002, Dan Olson wrote:

> 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

Watch out for address line A20. The IBM and clones use it, but it actually
comes from an I/O pin on the keyboard controller rather than the CPU.
Sorry, I don't remember any details.

The Intel databook for the 8088 is titled "iAPX 88 Book". Mine is dated 
July 1981, and has stickers on it indicating that it was actually 
published by Reston Publishing Company, Inc., a Prentice-Hall company. No! 
I won't part with it!

Re: hardware questions

[Dan Olson]

> Watch out for address line A20. The IBM and clones use it, but it actually
> comes from an I/O pin on the keyboard controller rather than the CPU.
> Sorry, I don't remember any details.
>
> The Intel databook for the 8088 is titled "iAPX 88 Book". Mine is dated
> July 1981, and has stickers on it indicating that it was actually
> published by Reston Publishing Company, Inc., a Prentice-Hall company. No!
> I won't part with it!

Thanks, maybe this kind-of leads into what has been confusing me a little,
that being how the 8086 and the newer 16 bit data bus CPUs talk to other
devices on the bus.  I only see a need for 19 of the 20 address lines
because only even addresses would be needed, the odd and even bytes would
both be transfered at the same time.  I'll keep hunting for more
information.

	Dan