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Northstar Horizon Questions

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Vercus

Experienced Member
Joined
Jul 9, 2009
Messages
123
Location
Pennsylvania
Hello,
I just recently acquired two Northstar Horizons with a Heathkit H19 terminal. They came with several disks, and I've been trying to figure out what I need to do to get one of them to work. When I power the system up, the floppy drive spins, but it doesn't boot, even after trying several different disks. I even swapped out the floppy drives and systems, and both do the same thing.

I can only use one system at a time right now, as I am short a memory board- it caught fire:confused:

I have a whole box of old hard sector floppies, but I'm assuming I can't write those with a modern DOS PC and a 360K drive, correct? What would be the best way at getting a known good CP/M or N* DOS boot disk? I've found some software on the internet, but have no idea how to write it.

On the upside, I have TONS of manuals for this thing! Just about everything I could imagine is discussed in there. I'll definitely pour into them and see what I can dig up. Still, it seems to me if the drive is spinning and a disk is in it, something should happen, right?

Thanks in advance,
Jon
 
Unless your system was configured with a boot PROM (which was rare), you are correct in that you need someone to send you a boot disk (I'm assuming your system is configured correctly, is not damaged, and that you do not have an actual working boot disk). I went through this same process when I purchased by Northstar a few years ago (I just sold it). Once you get a working boot disk (N*DOS), you will be able to use a serial cable and a small program to transfer disk images back and forth from a modern PC. This webpage contains links to that software and you should be able to figure it out (http://www.classiccmp.org/dunfield/). But you won't be able to do anyhting until you get a working N*DOS disk. Note: the program used for tansfers is under N*DOS not CP/M. So focus on getting the booting N*DOS disk, then you will able to make real disks to your heart's content, including CP/M. Full instructions can be found with those files at the link above. The good news is that Northstar systems had a fairly common configuration so these bootdisks are not impossible to find. A generous member of these forums helped me out.
 
I have both a Northstar Horizon and an Advantage with the same problem. Won't boot from what should be a good boot diskette. Your problem may be more than just a bad diskette or misaligned drive. If you do a search on this forum you should find other threads discussing this same problem. I have shelved my project until I have more time to work with them.
I did purchased a new boot diskette from Dynacomp Software. They are regular sellers on eBay.

Their recent listing is eBay # 380158017691

CP/M Boot Disk/Utilities - North Star Format Diskette
This disk will boot to the CP/M A> prompt on a North Star Horizon with a terminal connected to the serial port. You will need at least 24K RAM as it loads a 24K version of CP/M.

and eBay # 380158018280

NORTHSTAR DOS/BASIC Disk for ALTAIR/IMSAI/S-100
The Altair and Imsai computers really got going when North Star introduced the 5-1/4" 10-sectored disk drive; these computers then became truly useful. This disk contains two different types of BASIC (one for a floating point board), having various digit precisions. This disk also contains North Start DOS.
 
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I have a working N* and the last time I used it earlier in the year, it exhibited similar booting problems. Last time I worked with it, it booted just fine for part of the operating session and then stopped booting later in the same working session, giving me only a blinking drive light. Even after a cool-down period it still didn't work, so I don't think it's a heat-induced temporary failure.

I have read that it relates to flakiness with the disk controller (not that the design is flaky, rather that it goes out of tolerance somehow over time) but I haven't bothered to troubleshoot it yet (too many other projects). I did buy a spare MDS-2AD controller but I haven't swapped it in yet.
 
Wow, I must admit, this doesn't make me too optimistic about my chances of getting these things going! I wonder what could be causing the controllers to go? I question whether it is the controller on mine or not, as the drive does turn, it just doesn't seem to read the disk. I do get a clicking noise as the stepper motor moves a little bit, but it doesn't really seem to advance.

I have read about the need to lube drive rails. What would be a good lubricant to use? I have lithium grease, 3-in-1 electric motor oil, and WD-40 available. I'm guessing of those 3, lithium grease would probably be the best?

Any thoughts would be appreciated.
Thanks,
Jon
 
Vercus said:
Wow, I must admit, this doesn't make me too optimistic about my chances of getting these things going! I wonder what could be causing the controllers to go? I question whether it is the controller on mine or not, as the drive does turn, it just doesn't seem to read the disk. I do get a clicking noise as the stepper motor moves a little bit, but it doesn't really seem to advance.

I have read about the need to lube drive rails. What would be a good lubricant to use? I have lithium grease, 3-in-1 electric motor oil, and WD-40 available. I'm guessing of those 3, lithium grease would probably be the best?

Any thoughts would be appreciated.
Thanks,
Jon
Click to expand...


I don't think I've ever lubed the head carriage rails on my drives. I always thought they are zero-maintenance except for picking fuzz off of them. I have Teac and Tandon drives from the 80's that have had no maintenance of this type and work just fine.

If I had to lube them, probably white lithium grease would be the best. The other two are pretty thin lubricants and might spatter on the diskettes or otherwise collect more dust and grime. If you plan on doing this, I would put the grease on a Q-tip and then lightly run it over the rail and work it in by accessing the drive.

I personally don't think this relates to the problem, but having said that, maybe it's possible that if the head carriage is binding, the controller is timing out on a sector seek. I didn't think the tolerances were that tight, but I'm curious as to how you progress.

My N* uses standard PC floppy drives -- the Tandon TM-100A. I had to replace the original MPI drives because of blown motor controllers in both when I adopted the system.
 
If your not 100% sure you have a working boot disk, I would try that first. Its the easiest and problay most likely problem. Dave's NST utility works great, but there is no way to bootstrap the northstar like other systems because it has no ROM. There is no way to enter code (front panel, monitor program, etc.) without dos. I agonized over this for quite a while until someone sent me a boot disk. But if you are sure you have a working boot disk, then you are of course on the right track troubleshooting the hardware.
 
bugman2112 said:
If your not 100% sure you have a working boot disk, I would try that first. Its the easiest and problay most likely problem. Dave's NST utility works great, but there is no way to bootstrap the northstar like other systems because it has no ROM. There is no way to enter code (front panel, monitor program, etc.) without dos. I agonized over this for quite a while until someone sent me a boot disk. But if you are sure you have a working boot disk, then you are of course on the right track troubleshooting the hardware.
Click to expand...
---
Ah, I thought it was a similar situation as his CRT program which lets you create a boot disk over the serial port. I had a Northstar once but scrapped it long ago, so I don't remember much.

But this seems to be talking about a monitor ROM being available, or at least a place for it:

http://newsgroups.derkeiler.com/pdf/Archive/Comp/comp.sys.northstar/2007-05/msg00021.pdf

Maybe Andrew will see this thread and have some insights to offer.

mike
 
Yes, one of the boards had an option for a boot ROM to be installed. I can't remember which board (memory, CPU, etc...). But to my understanding this was rare to find one configured that way. Mine wasn't for sure.
 
bugman2112 said:
Yes, one of the boards had an option for a boot ROM to be installed. I can't remember which board (memory, CPU, etc...). But to my understanding this was rare to find one configured that way. Mine wasn't for sure.
Click to expand...
--
Well, there'd have to be a *boot* ROM, wouldn't there, or else how would you read the boot disk? But apparently they didn't all have a monitor that'd let you talk to it via RS-232...
 
I guess "boot" wasn't the best terminology to use. I meant what you said, it lacked any kind of monitor program for basic I/O that would initialize seperate from the drive controller. The CPU board did have a small component area where you could add a ROM (2708 ) as an autostart option. I 've not heard of many of them being populated, though.
 
I've got 5 or 6 disks that I'm told should boot- Northstar DOS and CP/M. I would think with that many disks, at least one should still be good, right? As far as boot PROM, mine doesn't have it. I'm travelling with work til Thursdaym but I'll have to check out that NST program when I got home. I hope I can get one of 'em going, as they're cool looking computers, and there seems to be a lot of boards made for S-100.
 
check the voltage regulators in the back left of thr moboard, the middle one especially. Your symptoms indicate that this may be bad. To confirm check volatage to the drive.
bill
 
bugman2112 said:
I guess "boot" wasn't the best terminology to use. I meant what you said, it lacked any kind of monitor program for basic I/O that would initialize seperate from the drive controller. The CPU board did have a small component area where you could add a ROM (2708 ) as an autostart option. I 've not heard of many of them being populated, though.
Click to expand...

Hi
How does the N* start if there is no boot ROM?
I don't think the disk controller is DMA based with an auto
boot ( I do have a ROM-less S100 but the disk does DMA ).
There is a monitor program for the N* but you need the
disk working before it will work( chicken&egg problem ).
Dwight
 
Dwight Elvey said:
Hi
How does the N* start if there is no boot ROM?
I don't think the disk controller is DMA based with an auto
boot ( I do have a ROM-less S100 but the disk does DMA ).
There is a monitor program for the N* but you need the
disk working before it will work( chicken&egg problem ).
Dwight
Click to expand...

Hi
A little research answered my question. The controller
has a small bootstrap loader ROM located at E800H.
This is how it boots, this is the boot ROM.
Dwight
 
billdeg said:
check the voltage regulators in the back left of the moboard, the middle one especially. Your symptoms indicate that this may be bad. To confirm check volatage to the drive.
bill
Click to expand...

I don't have the dox handy -- is this the 5v or 12v regulator?

Update: never mind -- I pulled out my N* last night. There's a trio of 7805 regulators in the upper-left corner, right above the 7812 TO-3 regulators. I tested the voltage at the drive connectors -- there is a slight difference between the voltages at either connector -- 5.02v and 5.12v. The boot drive is on the connector with the lower voltage. I guess there could be a transient voltage sag which causes the voltage to drop below 5v, but I'd have to put a scope on it to see.

The schematic notes that there are several bypass capacitors on the outputs of the voltage regulators supplying the disk drives that are not used (C5, C6, C8 and C9). The docs I have already reflect this ECO, so the parts list doesn't have the values. I don't know if it's worth populating those with, say, 4.7uF tantalum caps or something like that.


I will probably swap the power connectors and see if that makes a difference.
 
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Hello,
I have just about every manual made for the thing at home. I can take a look inside at the regulators, and between looking the part numbers up online, and looking in the manual, I should be able to find out which is which. They seem to be a common failure point. I have a DEC RL02 with a bad one as well. Hopefully I have the service manual for the N*, as that would be more helpful.

-Jon
 
Hi Jon,

As the former owner of the N* Horizons you are asking about, maybe I can help a little bit here -- with a little history, at least.

I tend to agree that it's not likely to be the boot disks that are the problem. Of course disks that old can go bad, but it's highly unlikely that all of them did. Of the box full that I gave you, there are many others besides the half-dozen or so that I pointed out that should boot if the hardware is good. The disks were stored in metal cabinets, in reasonable indoor conditions, so I believe that most if not all should work fine. One obvious way to check would be to send some off to someone with a working Horizon to try.

Unfortunately, the computers were stored in less favorable conditions. Although they were kept covered under plastic, they spent some years in a garage (the same one where you picked them up), where the temperatures can sometimes get below freezing during the winter even though it's part of the house.

Although I'm mostly a software guy myself, I sometimes found the extensive schematics that came with that old documentation useful. They really told you everything in those days! (The oldest of those two machines was purchased by March 1978.) Somewhere in there, I believe, with the right testing equipment and hardware skills, the answer will be found.

Although the disk controller boards are obvious suspects, I wouldn't overlook the memory boards as possibilities. One of those boards, the one with the post-it note, is definitely blown. For a (fun?) picture of the actual event, see

http://www.dropshots.com/joesulldux#date/2006-09-29/22:24:41

(The memory board is the frontmost, and you can just see a wisp of smoke still curling up from its left side. I had decided to put out the fire before taking the picture ...)

I hope this has been of some help, and wish you luck (and fun) getting these systems going.

All the best,
Joe
 
billdeg said:
check the voltage regulators in the back left of thr moboard, the middle one especially. Your symptoms indicate that this may be bad. To confirm check volatage to the drive.
bill
Click to expand...

Bill --

I started up the N* tonight and I got the boot monitor prompt for a few minutes and then all of a sudden it appeared that the system wouldn't reset (or at least I lost the console connection). So, on a lark, I put a probe on a random 74xx chip on the motherboard and I got 4.88v. That seems a bit low to me.

I'm thinking that not only is the 7805 regulator for the drive flaky, but maybe the regulator for the motherboard is as well. I took off tomorrow so I added this to my list of things to tackle. I have a few 7805s laying around so I'm going to replace both and see what happens.

UPDATE: I replaced all three 7805 regulators. The reported voltages on all three are 4.97v. Interestingly, it did restart once and give me the "NORTHSTAR..." monitor banner, but refused to accept input. Shortly after, it wouldn't give me the startup banner and the drives won't spin up.

I have to go out for a while, but I'm going to try it without the floppy card and see if I can just get the CPU working.
 
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