Northstar Horizon

jim stephens jwstephens at msm.umr.edu
Sat Nov 25 05:27:54 CST 2006


Dave Dunfield wrote:

>
>I have many images for both single and double density Horizon systems on my
>site - if It's SD, your choices are NorthStar DOS and my own DMF system. If
>DD, the choices are NorthStar DOS, CP/M and UCSD Pascal.
>
>But you will have a bit of a "chicken and egg" problem - the NorthStar disks are
>hard-sectored, which means that you can only make them on a system with
>the NorthStar controller. Unless you have other N* systems kicking around
>you will have to use the Horizon.
>  
>
Dave,
thanks for mentioning your site.  I knew someone had some material 
online, and it is probably you
I was thinking of.

As to the chicken or the egg, I took the approach of getting the bios 
code to run the horizon
controller, and generated a horizon CPM that would run one of my Tarbell 
controllers in the
box with the Horizon controller.  it only took a bit of editing to boot 
the cpm with both, and
it would sysgen and format either diskette, 8" or 5 1/4" and also run 
pip for copying
data to and from each format.  I just split it up so I had 2 drive 
letters for each type, so
A,B was one, and C,D was the other. 

I flipped the code and merged the horizon code into the tarbell code later.

I don't recall back then as to my chicken and egg problem which was how 
to get the sources
needed to do the tarbell onto the horizon, but I think I captured a 
listing via a serial program
and edited the tarbell bios stuff into the cpm on the horizon.  After 
this bootstrap, which
involved maybe a hundred lines of code, I could merge up enough to do 
everything via
diskette, then finish.

Now, if you have access to moving data from a simulated CP/M to 8" and 5 
1/4" you
could do the editing anywhere, and go back to the 5 1/4".

but someone has to bootstrap you onto the 5 1/4" northstar, since it is 
pretty much one
of a kind.

many different ways exist onto 8" but the problem dave mentions means 
you have to
start up somehow with a few 5 1/4" diskettes, and generate your boot, 
and I assume
a way to assemble, test, then use the horizon bios, so you can adapt 
what you need.

The only thing that a true horizon has is a 256 byte boot, and I don't 
know of anything
that does anything but floppy booting exists.

I remember the boot rom gets mapped into somewhere in the Exxx range, 
and reads
in a 256 byte sector, then jumps to it, before going away.  I don't 
think you could
pull it and get a serial program into it to read one of the serial 
ports, but I won't say
never to the crowd on this list.

And my memory of 256 bytes may be off, I vaguly recall maybe on 32 bytes 
are visible
and used by the processor at boot.  People had to use pretty small proms 
in the early
days of the hobby.

Jim



More information about the cctech mailing list