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Northstar Horizon DOS on any S-100


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  Northstar Horizon DOS on any S-100 by Bill Degnan - 11/06/2011 22:15
Been working for the past week and a half to build a set of hardware that I can install into any S-100 computer that will boot the Northstar Horizon DOS system. So far I have a working MDS-A3 card, disks, dual external drives, cable. I am working with various monitor programs to fit the DOS bootstrap at E800 into the system. Been experimenting with different approaches. A lot of work without much to show for it....yet

I have also in parallel been trying to get *any* Micropolis disk drive to boot (FDOS).

I have a Vector Graphic ZCB single board computer with something called the Northstar Monitor 1.5. Using this as the processor card I can then activate my DAJEN Prom card with DAJEN monitor program to burn ePROMS. The idea is that once I get a working system I can burn it into an ePROM(S).

I have a serial switch box that I can use to jump to the differently-configured monitors. The DAJEN requires a null modem cable, the ZCB is straight through. They're both set for 9600 baud.

This is one of those "onion" cases. Every time I solve one problem another pops up. For example I cannot figure out why the MDS bootstrap is not being written into RAM even though I have PHANTOM of te ZCB open, and the PROM for the monitor stops before E7FF (it's a 2716). I burned a couple 2708's to hold the monitor program thinking this might work instead of one 2716 (re-jumpered the ZCB for 2708's), but the card hates that config and locks up cooking the PROMS in the process. There are some hacks on my particular ZCB, not sure what they do. This is real computer archaeology stuff.

  Personalizing NorthStar DOS I/O Ports by Bill Degnan - 02/21/2012 09:00
I am using a known working MDS card with known working disks, cable, and external dual drive. I can boot this combo from within a N* system just fine because the port settings of the OS match the motherboard.

I re-jumpered the ZCB to allow the Northstar MDS PROM to load into E800 without interference by the ZCB. I am using a newer stable Tanner 64K RAM card with the last two pages empty (E and F)

The ZCB Serial Port by default is set for 04 (control) and 05 (data) as far as I can tell.

I can boot a disk successfully and load the OS to 2000H, but as the NorthStar OS manual predicts correctly I should not expect see anything to the screen, nor be able to enter commands from the keyboard, without personalizing the DOS.

Using the monitor program installed on the ZCB I can get to and edit the OS code written to 2000-2A00. (The bootstrap writes the OS to this location) I am apparently set to personalize N* 5 to work with the ZCB ports.

The I/O routines are located in 2900-29BF.

The N* DOS I/O routines expect output port = 3 input = 2, according to the N* hardware manual see: page 40 and 34-35.

To Determine:
Would I edit the values in memory such as 29AD - D303 "output to port 3" ??... or do I have no choice but to change physical jumpers on the ZCB ? I am sometimes confused by what N* means by ports vs. what I think ports are.

See page 19 from

http://www.s100computers...20System%20Overview.pdf (see page 12-16)

...with this info I will go the personalized version of DOS route. The example is for the MITS SIO at port 0, but I can adapt to my needs. And while I am at it, make a personalized DOS for my Altair.

  Hardware Solution ZCB and Northstar DOS by Bill Degnan - 02/23/2012 00:07
I have asked around for assistance to personalize Northstar DOS 5 to use the Vector Graphic ZCB running port 4/5.

In the mean time I will make the following hardware change to the ZCB to be compatible with Northstar DOS (and presumably CP/M for Northstar)

Jumper Pad G 9-6
Jumper Pad E 1-4
Cut jumper B

This will cause the ZCB use port 2/3 and to NOT autoload the PROM monitor on E000, but I now need a way to load N* DOS instead... perhaps a ePROM that does nothing but call E800

  CP/M for Northstar MDS using custom port by Bill Degnan - 02/26/2012 22:40
Lifeboat made a CP/M that one could customize to use port 4/5 of the VG ZCB Northstar monitor 1.5.

The plan would be to gen a new copy of CP/M using a Northstar Horizon running standard CP/M for N*, and then attempting to boot this special disk on another system with the ZCB setup.

  Personalizing CP/M2 24K on Northstar by Bill Degnan - 03/18/2012 13:25
On page 9 of the Lifeboat CP/M 2 manual for Northstar controller, there is a list of compatible I/O controller cards, and the associated ports.

NEXT - Try Northstar DOS on a stock IMSAI.



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