Nice Northgate!

As I've continued to learn about Minnesota's computer history and the history of the PC compatibles, I've learned that Minnesota seems to have had more than our fair share of successful PC clone builders.  Perhaps this was a lingering effect of Minnesota's strength in the early days of computing with Remington Rand and several of the the mainframe companies located in Minnesota (IBM and the Seven Dwarves).   I know of at least one individual who left an engineering job at a mainframe company in order to run a business building PC clones.

Many of these companies didn't have the market size to design their own boards, and so they would purchase and build systems using boards from many different vendors in Taiwan, but there were a few companies that either started early enough or had a large enough market share to do their own motherboard designs.  There were a couple of local companies that Minnesotans might recognize, ZEOS and Northgate Computer Systems.  Both advertised nationwide, and so had some broader recognition.  It seems that both struggled with financial trouble in the mid 90s, Northgate going through a bankruptcy and Zeos a buyout.

I've been interested in Northgate since I've had one of their keyboards for a while.  I was recently offered one by a collector in St. Paul who is looking to downsize.  The machine was untested, but I was able to look inside and ensure that there wasn't battery damage.

When I got the machine home I unplugged the mainboard and checked the Power Supply voltages.  Everything checked out, so I plugged it back in and it booted.  Of course the clock battery was dead, but I was able to set the BIOS parameters and boot off a floppy.  I was not able to figure out how to set the BIOS to recognize the hard drive but after some time I realized that the Specifications sticker on the back of the machine listed the Hard Drive's BIOS type on it.  When I entered that data in the BIOS the drive was recognized right away and the machine booted to DOS 6.22.  There was a Drive Overlay installed on the HDD to get it to recognize the additional space on the drive, it has a 450 MB drive that appears to be working just fine.

One of the next challenges with this machine was determining which Northgate system it was.  There is not a ton of information available online about these systems, but I found this list on Vogons.  By googling images, I was able to determine that this was a Northgate Slimline 320 (A 386 @ 20 MHz with a date of 1991 on it).  Knowing the model I was able to find these jumper settings and specifications.  It turns out that this unit has already been maxed out at 8MB RAM.

After this, I needed to decide what to do with the machine. It has a total of 3 16 Bit ISA expansion slots, and two 8 Bit slots on the back.  It had a modem which I removed, and replaced that with a generic sound card.  I have a not quite period correct, but significantly cheaper Sound Blaster Vibra 16 on order for this machine.  I also used the slightly newer 3COM 3C509B 10MB Ethernet card.

For storage, I tried directly connecting a Compact Flash card to the IDE Bus on this machine, but I was not able to get the BIOS to recognize the newer cards that I had (2GB and 4GB Sandisk and 1 other brand).  I wouldn't have minded if I could only get those cards working with 250 or 500 MB partition, but nothing was working so I installed a Lo-Tech XT-IDE card that I already had on hand from another build that I changed.  This boots the machine just fine.

Once I got DOS and some of my standard Games and Utilities moved over to the Compact Flash drive, I tried to install Windows 3.1 on this machine.  The machine has Integrated Graphics, and when that is enabled, a boot message indicates that the video card has 256K RAM onboard, which is enough RAM for 640x480 with 8 bit color.  However, I could not get this to work with Windows 3.1, either on the original Hard Drive or on the CF based storage.  Windows 3.1 locks up after the splash screen.  This makes me wonder if the reason this machine was taken out of service back in the day was because of a failing video controller on the motherboard.  Anyway using the board Jumpers I was able to disable the onboard VGA, and test several other 16-bit ISA Video Cards that I have.  I decided to use the most "period correct" VGA card I had.  This came from another 386 parts machine, and it also has only 256K RAM on it.  This works great in Windows 3.1, but of course has no acceleration, which is just fine for this machine.

So that about wraps it up for this machine.  I'm really happy to have a nice clean Northgate Computer in the collection that pairs nicely with the Northgate Keyboard that I've previously blogged about.

Please let me know if you have any memories of using Northgate Systems back in the day, or any tips about where to find additional technical information about the Slimline systems online?

Retro Computer Keyboards - Northgate Omnikey 101

 Recently, I had a challenge to find an XT compatible keyboard for a project I'm working on, a Tandy 1000 RL which I’ve covered previously on the bLog here.

I ended up going a couple of different routes on solving this problem, but the one I'll cover in this article is the Northgate Ominkey 101 that I found on eBay.

Northgate was a Minnesota based manufacturer of Clone PCs (A PC Assembler).  They were profitable enough that they had their own custom designs being built for them, including keyboards.  These are classic keyboards of their time, with a metal backplate, and "Complicated White Alps" mechanical keyswitches with a really great feel.

I stumbled across this keyboard while searching eBay for AT/XT Compatible Keyboards for my Tandy 1000 RL project, and the listing intrigued me.  The seller indicted that one and only one key was not working.  I was hopeful that I’d be able to fix the one key switch that was not working, and was able to get the keyboard with a surprisingly low bid.  I was also able to find a full manual for the keyboard online and read through that information.

The first challenge was that this keyboard does not have an attached cord, so I ordered a PS/2 male to PS/2 male cable used on eBay so I’d be able to plug the keyboard in for test when it arrived.  Also, I assumed that the reason one of the keys didn’t work was that it had a bad key switch, so I ordered 10 replacement keyswitches as well.

When the keyboard arrived, I tested it and it was indeed as the seller had stated, one and only one key did not work.  Here’s what the keyboard looked like when it arrived...

I started by testing the continuity of the key switches with the ohm meter, and to my surprise the suspect switch was working, so I was not going to get the “easy win” with this keyboard.  After poking around at the circuit traces, I remembered that the manual was very detailed.  Going back and looking at the manual, it includes a complete circuit diagram for the board.  Using the diagrams, I started to poke around more on the board testing continuity at various points, but after checking both the row and column that the key switch was on, I realized that the circuit diagram showed a small signal diode wired in series with each and every keyswitch on the board.  After finding this out, I was able to isolate a fault, the small signal diode on the switch in question had opened up.  I was able to repair this by putting another diode in parrallel, soldered to the back side of the board, since getting to the top side would have required completely dis-assembling the board.

Once I had the electrical problem resolved, I took all the key caps off, cleaned them with soap and water, and retrobrighted the key caps and top of the board.  While I was putting the circuit board together, I noticed that the PS/2 connector inside the keyboard was broken.  I tried to repair this with Superglue, but the repair failed because the glue filled the gap and I could no longer plug the connector in.  Short term, I was able to make a keyboard cable by cutting off one end of the cable and soldering it directly to the board.

With the board both working and looking nice I was hoping to address a couple of small things, the missing keyboard door over the switches, the broken PS/2 connector, and the now missing cable.  While googling around to learn about these keyboards, I had encountered this online buisness specializing in fixing up and reselling these boards.  I reached out via email and the owner of the buisness was quick to respond, and he had all the parts I needed to get the board back to factory condition, and at a reasonable price.  I’ve just installed those parts today, and I’m super happy with the keyboard.

Originally, I bought this board to use with an XT class machine, since I didn’t have any other options, but this keyboard has ended up looking so nice and having such a great feel that this will take its place on my desk as my “Daily Driver” for a while, replacing an Apple M0116...

Thanks again to Bob @ Northgate-Keyboard-Repair.com for the assist on this one, without his help I would not have been able to get the parts to return the board back to factory new condition.

Did you ever have a Northgate keyboard?  Or what is your favorite keyboard from retro computing history?  Please leave a comment below, or feel free to send an email.