My First 486 Build

I’ve always had a soft spot for the 486 since this was the generation of the first PC I ever owned. Getting a 486 has been on the short list of computers I’ve been wanting for quite some time, but I've been holding off because of the price.  I'd love to buy my original 486, a slimline Gateway product from 1993/94, but they have become both rare and expensive.  The next best thing would be to do a build from the era which would be a great learning experience since I wasn't doing builds at the time.  Frankly, at the time, I didn’t know enough about computers to do a build, but thanks to the Internet and the willingness of the Vintage and Retro Computing community share their knowledge, this is no longer the barrier than it once was.

One of my retro computing friends had a board from an old build that he wasn't using, and he sold it too me at a good price, along with a Cyrix 486DX2-66 Processor and some RAM.  This is a 386/486 board with VLB.  It was an offer I couldn't refuse, even though I didn’t know where I’d find a case.  Within a few days a case popped up on Craigslist from a trusted seller, so at that point I knew I had to start the project.

I was able to gather the parts and start into the build.  The case was a donor from a PC with an older 386 Motherboard that had an exploded battery.  It had been cleaned up some years back, but the board has an A20 Gate Error on boot.  I did some preliminary troubleshooting on this, but as the seller had already warned me, there was nothing obviously wrong with the board.  I may come back and make another attempt at repair later but I set the older 386 board aside for now and turned to cleaning the case.  This was a system from 1990.  It was dirty and the plastics had yellowed, as you can see here...

I took the case apart, and took the LEDs and switches out, just as you will see many of the smaller YouTube channels doing like Necroware and RetroSpector78.  I really enjoy the process of cleaning this old gear up and getting it looking better again.  Sometimes it's not possible for me to get it back to complete like new appearance, but I know I got the case front looking significantly better...

The plastic front still doesn't quite match the painted metal, but I don't have a very powerful UV light on my retrobright tank, so it took a couple of days to get too this point.  I may need to think about an upgrade at some point on the UV LEDs in the tank.

Once the case was cleaned up it was time to start the build.  The 486 motherboard I already mentioned has a BIOS on it from 1994, so I decided that the timeframe for the build was going to be a system  thats started out in 1990 (with the case) and had gotten upgraded over the years up until the mid 90s, I didn't want to use any gear in the build later than that.  Also, I didn't want to spend an arm and a leg, so that meant (mostly) making do with parts I had on hand.

One of the first things I needed to deal with was cooling of the 486DX2/66.  I had a heatsink from a Dell machine, but the heatsink alone wasn't enough.  Since there isn't much airflow in this case, I added a fan inside to blow air directly over the top of the processor while the machine is on.  This keeps the CPU cool to the touch even after hours long periods of use.

The specs of the build at the start were:

486DX2/66

5MB RAM

Cirrus Logic ISA VGA Video Card w/ 512 KB RAM

16 Bit ISA Disk Controller Card w/ IDE2SD Adapter, and 1X Sony IDE CD ROM

Super IO Card for Serial / Parallel ports

Opti 82C929A Sound Blaster Compatible

Being the first project of this kind that I've tackled, there was quite a learning curve.  The early PC stuff that I've worked on really doesn't have that many options and frankly you just can't get that much performance out of them,  This 486 system is pretty different.  I was easily able to get the system up and running, but the performance was horrible when I ran the tools in Phil's DOS Benchmark Pack.  (3 fps in SuperScape) And probably more important, it didn't perform anywhere near what I remembered from my 486 in games like Star Wars X-Wing, Wolfenstein 3D, Doom, etc.  I got discouraged and put the build on hold for a couple of weeks because of this.

I tried quite a few things to remedy this situation.  First, I did a RAM upgrade, bringing this machine up to 20 MB RAM, which would have been a shocking amount of RAM back in the day.  My PC had either 4 or 8MB at that time.  Sadly, increasing the RAM did not help.

I also asked for advice from a friend at Free Geek Twin Cities about doing a VLB upgrade of the Graphics card and Disk Controller, but that was going to end up costing almost as much as the rest of the build just for those two cards so I abandoned that idea.

I ended up going through the AMI BIOS settings one at a time, googling those settings that I wasn't familiar with, and trying to understand how those affected machine performance.   What I ended up landing on was this article on the Vintage Computer Forums.  The key to unlocking the performance on this machine was the AMI Bios setting:
Advanced Chipset Setup / AT BUS Clock
The default value was CLK1/6
I changed this to CLK1/4 saved and rebooted.

The machine performance was vastly improved (27 fps in SuperScape), and more important, X-Wing runs like it should.

There were various other minor things that came up along the way during the build but after the bus speed was set correctly the machine has been running really well.  I’ve been getting a lot of enjoyment out of it.

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.

A Tandy 1000 RL HD Repair Story

The Tandy 1000 series is a really interesting series of clone PCs.  For me, the fact that it’s an American designed PC clone and not an IBM product makes it more interesting.  I'm not fond of IBM, for reasons that I've mentioned before.  As a kid, Radio Shack was always my favorite store, and I remember wanting one of their computers.  Today I have a strong interest in these XT class machines because of the limitations that this processor imposes.  I have one of the first XT based PC clones, the Compaq Portable from 1983, but this would have been one of the last XT clones, a Tandy 1000 RL HD from 1991.  Tandy took the XT just about a far as it could go, with really good built in color video and sound.

One of my retro computing friends is really into PCs and has a great deal more knowledge and experience with this era of systems than I have.  He's shared his interest in the Tandy 1000 series of computers with me, and I’ve been wanting to get one as I've become more interested in the history of PC gaming, learning from Neil @ RMC's excellent Tea Break series, and from the 8-Bit guy's video here.  So, when my friend started having trouble withe one of his 1000 machines and offered it to me as a repair project, I jumped on the opportunity!

The computer was non-functional and since neither my friend or I had another one, we were not able to do parts swapping to determine exactly where the fault lie, but he was pretty certain that it was the Power Supply, which made the most sense.  He pointed out this video from the YouTube channel Necroware about making a Power Supply for a Tandy RL using a 12V Power Supply and a Pico-PSU, a rather creative idea.  Also, I looked on the Vintage Computer Forums and read this article about buying a different off the shelf power supply that could work.  Unfortunately I did not think the Jameco power supply would fit inside the slimline case of the Tandy 1000 RL, so I ordered a Pico PSU that I found for sale on eBay.

When the Pico PSU arrived, I carried out the Power Supply upgrades very much like what you see in the video.  During the repair, one of the mistakes that I made was taking the main power switch apart to see how it worked.  These switches have a lot of small parts and springs inside and I was not able to get the switch properly re-assembled.  As a work around for the broken power switch I wired up the PSU to be on all the time, but sadly the new power supply didn’t work.  In digging in a bit more on this, I remembered that the -12 Volt current rating on the Pico PSU I bought was 100 mA max.  The rated current of the computer was also 100mA, so I thought that this would be OK when I bought it, but it was not enough current (it's likely that aging components on the motherboard consume more current than they used too).  The power supply voltages all looked good, but the moment I plugged into the Motherboard, all the voltage would go to zero. (Short circuit protection.)

At this point I still suspected that I had a bad power supply, but I was wondering also if there was something going on with the Motherboard.  I setup a saved search on eBay for a Tandy 1000 RL for parts / not working.  I also tried to find another Pico PSU with a higher current rating on the -12 volt rail, but that was a dead end at least at that poin on eBay.  I ended up putting the entire project on hold for several weeks.  I didn’t know what to do, and I had other things to work on, so the project sat.

Then something unexpected happened, a cosmetically damaged but working Tandy 1000 RL HD came up on eBay from my saved search.  I tried not to get too excited about this since it was a 7 day auction that might have gotten bid up, but the seller had done a good job of documenting the condition of the computer, so it was not going to collect top dollar.  I put in a minimum bid at the beginning of the auction and I had to raise my bid once towards the end, but I ended up getting the machine for what I considered a fair price even with the shipping.

When the "new to me" machine arrived, I was able to swap in the power supply and confirm that the first machine was working.  It booted for me for the first time, always an exciting moment! The end result of the troubleshooting exercise was that the Power Supply had been the problem all along.

The next problem I faced with this machine was the keyboard.  My other XT machines have built in keyboards, so I didn't have a working XT Class keyboard.  In talking to several different retro computer friends I learned that these are quite difficult to come by now.  Perhaps the cheapest solution is the AT2XT converter project.  These are for sale on eBay, but I have not received and tested mine yet, so I won’t link to that.  Another good solution is a “Switchable Keyboard” that can do either AT or XT signaling.  These were more common during the transition time between the standards in the late ‘80s early ‘90s.  I was able to find one of these on eBay for a reasonable price.  With this keyboard plugged in I was finally able to use the Tandy 1000 RL for the first time after owning it for months.  This was another high point for me, and I really savored the moment.

One of the first things I did was fired up my copy of Planet X3 to check out those Tandy Graphics and Tandy Sound used to the best of their ability.  Planet X3 never looked or sounded so good on any XT class machine!  I look forward to digging in on other games of the period that have a special Tandy version.

The next order of business for this machine is to get working storage solution.  The machine I bought on eBay had a hard dive in it, which surprisingly still worked after shipping, but died within a couple of weeks after that.  I had an XT-IDE card to put in this machine, and installed that in the machine for Mass Storage.  I'm out of 2GB CF cards, so I'm currently running the machine off an old 16MB CF card that I had laying around.  Running out of Hard Disk space so quickly is part of the Retro Experience, but I do have some larger CF cards on order.

So that's it for the Tandy machine for now.  I may eventually find the correct "Tandy Enhanced Keyboard" for it at a reasonable price, but that's really about the only other upgrade I'd like to put in this machine, and in the meantime I will just continue to enjoy it like it's 1991.

Starting the New Year Right - Macintosh 512K - Part 2

As I mentioned in the last bLog post, I've recently become the next owner of a Macintosh 512K computer.  One of the first things I'd do with most of my Retro Computers is figure out how to get some kind of Flash Storage solution going for the system, but my goals for this system have been somewhat different.

One of the main things I was hoping to get out of this was experience and a workflow setup for creating bootable Single Sided, Double Density (400K) Floppies for the earliest Macs from Disk Images.  That's been an ongoing interest of mine, and one I've bLogged about before a couple of times.

I've had good success in the past creating 1.44 MB and 800K floppies for Mac OS installers from disk images from the Internet, using a Beige Power Mac, but I was really struggling with 400K disk images.  You can find disk images on the Internet and suggested workflows, but I was not able to use any of the downloaded disk images I could find with Disk Copy 4.2, as the resource fork from these disk image files had been stripped and the files were no longer useable with the older version of Disk Copy.

Then I remembered my FloppyEmu.  These are a bit expensive so I have only one, and usually have it connected to an Apple II computer.  Moving it onto the Mac requires that the firmware be re-programmed, it's not a huge task, but I usually avoid it.  At this point, I could avoid it no longer and I'm glad I didn't because it ended up being exactly what was needed.

As a test, I started out with my Macintosh Plus because I can boot it from SCSI2SD and I have a large range of OS choices, for this, I choose 6.0.8 because it's got good native support for the 400K disks, so the disks I'd image would be immediately readable and testable on the disk imaging machine.

I started out with Mac II Disk v. 5.2, and used the settings shown here...

I apologize for the scanlines on the screen, but to summarize, we are doing a single-sided, sector by sector copy from FloppyEmu too the real internal floppy drive.  This worked great, and how I have a floppy disk set with Mac OSs from 1.1 up to 3.3 on 400K floppies that work great in the 512K.

However, this method isn't perfect because it requires the use of the FloppyEmu each time.  (as I've mentioned, I prefer to leave this connected to an Apple II).  So, I fired up Disk Copy 4.2, and used it to grab backup copies of the disks from FloppyEmu as .image files, with correctly formatted resource forks.  I have these files safely backed up to the cloud, as well as ready to go on my disk imaging rig any time additional floppies are needed.

These are all files that ship on FloppyEmu, just in a different file format that should work with the workflow I've described.  If you have any comments, questions, or feedback about this workflow or the files, please let me know!

Starting the New Year Right - Macintosh 512K - Part 1

Happy New Year, everyone!  I'm starting the new year right with an exciting addition to the collection, the Macintosh 512K, released in late 1984.

I'm really enjoying this system, and started out by doing a bit of "Computer Archeology" on this system.  One of my favorite things about Retro Computing is trying to figure out the back story on the systems.  For a couple of my systems I know they were purchased new by a family and held by them till I got them, but most of the systems have a certain amount of mystery associated with them.  This system has a couple of service stickers on it, and the previous owner (a fellow collector who has been doing this much longer than me) told me that he had swapped the Logic Board to get this machine back up and running again.  So I actually have more background on this computer than I do on most of the computers in my collection.

This system has a case from an Original Macintosh with a Serial Number that indicates that it was made in the 14th week of 1984, which I believe makes this case one of the first one hundred thousand units sold.  However, like so many of these units it was upgraded too a 512K board early in its life.  There's a sticker inside the chassis that indicates it was serviced at Heathkit Electronic Center on 6/15/1987 and this sticker has 512K printed on it, which seems to indicate that the upgrade had be carried out on or before that date.  The floppy drive and Power Supply board also have 1986 dates on them, so they may have been swapped at that time as well.

There is another sticker on the bottom of the chassis for a repair carried out at Midwest Visual Equipment in New Berlin, WI on 12/30/92.  This demonstrates that the machine was still being used 8 years after it was new, and used enough that it was worthwhile to have it serviced again.  I have no idea when the computer would have stopped being used, but within 2 years after that service the Power Macs were starting to be introduced.  That would have been quite the performance gap at that point in time.

As I've already mentioned, the main logic board was replaced more recently than any of the other repairs.  I don't know the date of the board itself, but the latest date code on the chips is from the later half of 1984, so this may have been a board from an earlier 512K example.

This computer has an 800K floppy upgrade.   I didn't think I'd be able to use that drive capacity since the 512K has the smaller ROMs (There's no code on the ROMs to run a double sided drive), but I've just learned that if you use System 3.2 with HD20 hard drive support, the ROMs get patched to support double sided drives both internally and externally.

All in all, I couldn't be more pleased with this addition to the collection.  I've always wanted one of these early Macs.  This is a good, solid machine in great repair that I don't have to feel bad about using since it's not a museum piece, which is perfect, since I do intend to use this machine.

I had quite an interesting challenge getting a workflow setup for disk imaging to create 400K disks for this machine, stay tuned, I'll go into that in Part 2 of this series.

What was your first Macintosh?  Let me know in the comments below if you have stories about these early Macs.