Northstar Horizon

jim stephens jwstephens at
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.
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.


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