Tech Thursday: NorthStar Horizon

NorthStar Horizon

NorthStar Horizon

This past February, Curt Michel, the Andrew Hays Buchanan Professor Emeritus of Space Physics and Astronomy at Rice University and former NASA astronaut, passed away. Michel taught at Rice for 37 years before retiring in 2000, but kept an office on campus to continue his research on “solar winds, radio pulsars and numerical methods.” I was never fortunate enough to meet him, but reading through the articles and obituaries, I can begin to grasp both the breadth of his academic achievement and the depth of the loss felt by the Rice community.

Curt Michel, 1965

Michel donated his academic papers to the Woodson Research Center in 2009. Included among them was an NorthStar Horizon. Released by NorthStar Computers in 1977 and recognizable for their unusual plywood housing, Horizons were popular computers, especially in universities, where they were capable of interfacing with a variety of control systems.


Horizon, Front: disc drives visible

There is a lot information about Horizons on the internet, but I think I will let Jim from the take it from here:

The Horizon, Aaaahh.. What a beautiful machine. It had a big honkin’ transformer for a linear power supply. It was the first product incorporating its own disk controller (see below), a 4 Mhz 8080, 4 KB of RAM standard, and 1 or 2 Shugart 5.25″ floppies. RAM could be expanded to 16 Kb.

The Horizon evolved with a faster (8 Mhz) Zilog Z80, and 64 KB of RAM. Then there was an accounting system called TSS/A that made the Horizon multi-user. It consisted of the main processor board, with multiple memory cards in the bus, and an 8 port I/O card for the other terminals.

The final crowning glory of the Horizon was a multi-user system called Turbo-Dos. This used the original processor as a controller, and auxiliary processor boards were added in for each user. They were called 8/16, because they could run at 8 or 16 bits. Each user had their own processor and memory (64K) and connected via boardlets from the main machine.

Another interesting fact – NorthStar was one of the early adopters of the hard disk drive. It was called the HD-18 – 18 Megabytes in an 18 inch platter. The drive was as big as a very large suitcase, and weighed about 70 pounds! You could daisy chain up to 4 of these, but the starting current was 13 amps, and when you lit them up all the lights in the place would dim.

NorthStar’s first product was a disk controller for the S-100 bus, namely for Altairs. It controlled Shugart 5-1/4″ drives, but using a proprietary format of 10 sectors hard-sectored floppies. This meant that the floppies needed 11 holes near the center, (1 index, and 10 sector markers) which was not the norm. Most floppies had one index hole

Its possible Michel collected data for his research and classes on the discs read by this computer. Unfortunately, I have not been able to locate any of the discs in the collection so far, and it’s doubtful if the machine could be restored into a condition capable of running them. You can see the fuse on the back is shattered.


Horizon, Back: Fan, power, and broken fuse



Curt Michel, 1934-2015

3 thoughts on “Tech Thursday: NorthStar Horizon

  1. The NorthStar Horizon was a top-of-the-line S100 bus machine. Big power supply and an active motherboard that did not need bus repeaters.

    You have a very nice example. The wood case was optional and many of them are scratched up.

    The broken fuse is a trivial thing, easily fixed in a few minutes with needle-nose pliers. Pull out the broken bits and put in a new fuse. But I’d check the caps before plugging it in.

    New, in the late 1970’s, this would have cost $2349 assembled, before any special cards were added. Inflation-adjusted, that is over $9000 today. Alternatively, it was just a bit less than Rice tuition at the time.

  2. Great info on the Horizon Northstar. I had one of these, connected to a Lear-Siegler ADM-3A terminal, and a matrix printer. It was a really good machine. I started with 48K, upgraded to 64K, and ran Sorcim Pascal, which had a paging mode in the compiler, so you could write a real application, and page sub-routines in from the floppy disks. It ran CP/M (Control Program – for Microcomputers), which was basically the design-spec for MS-DOS. I remember taking the NorthStar into my client at the time, which was a government treasury office (essentially the “Ministry of Economics”), where they had just bought a DEC-20/20, and showed them that the little CP/M box could crunch numbers and maintain data almost as well as the “big” DECsystem (a “mini”-computer) they had just installed. This was *before* the IBM P/C was released, circa 1981. The little NorthStar really was a beautiful product. I recall I sold it to another guy who had one, and I think I got what I paid for it. Of course, wish I had kept it. It is a piece of history now… a physical picture of the future, in a pretty wood-grained plywood case.. – Rus, GEMESYS Ltd.

  3. Yes, this North Star Horizon computer could easily be restored.
    There is an active group, that restores S-100 bus computers and designs new boards (and 21st century capabilities).


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