Compaq Portable III 286

 RESTORATION PROJECT

COMPAQ PORTABLE III

My first post on the blog and my third restoration project which is pretty much finished, is the Compaq Portable III. I got this fairly cheap on a local ad (Finn.no) and decided to continue my recent interest for old, retro, vintage computer stuff.

Specifications:

Compaq Portable III

Model: 2660
Released: 1987
Price: US $4,999.00 w/ 20MB HD
US $5,799.00 w/ 40MB HD
Weight: 20 pounds/10 Kilograms.
CPU: Intel 80286, 12MHz 

FPU: Intel 80287, 8MHz (installed recently)
RAM: 640k, 2048k max. (planned expansion)
Storage: Compact Flash ~650MB  CFtoIDE (20MB HDD originally)
1.44MB 3.5 inch floppy (1.2Meg 5-1/4 inch floppy originally)
Display: 10" gas plasma screen
640 X 400 resolution
80 X 25 text
Ports: RGB, serial, parallel
Expansion: Optional external expansion
OS: MS-DOS 6.22 and Windows 3.0 (MS-DOS 5 originally installed. Compaq DOS 3.31 installed from factory)

Source

The "luggable" computer happens to be the same age as myself. And I figured I could make this a nice addition to my yet very small collection of vintage computers.

First run

When I first started it up it booted straight to MS-DOS 5; which seems to be an installation by the previous owner as it seems it originally came with Compaq DOS 3.31. However it ran fine with the newer DOS-version, though a few errors in the AUTOEXEC and CONFIG-files which were apparent in the start-up sequence. But no biggie as my intentions were to wipe the 20 MB HDD clean and reinstall from scratch, and possibly even replacing the drive with a larger Compact Flash to IDE-card for better performance and reliability.

The hard drive was full of some interesting programs from the late 80's/early 90's used by the previous owner who was involved with programming back in the days. There were a bunch of old DOS-games which I eventually transferred to my IBM model 50Z.

The mounted 5.25" floppy-drive seemed to work as there were normal sounds and a disk light from it. But I was unable to read the two included disks, and figured there was a setup/BIOS-error.

The keyboard cable was all crispy and degraded. This would have to be replaced at some point.

First steps - floppy drive and HDD

There were no diagnostics-/setup-disks included when I got it. In the leather bag I found two 720 KB 5.25"-floppies. I tried to run them in the mounted 5.25" 1.2 MB-drive, but couldn't run them. I just got the standard "Retry, Abort, Fail"-error though I could hear the drive trying legitimately to read the disk. On my IBM I had an external 5.25" drive from Sysgen that didn't have any problem reading them. I tried to make a diagnostic disk with the installer from this site, but couldn't make one as it didn't recognize the external 5.25"-drive as a 360 KB-version. I therefore formatted one of the floppies with the "FORMAT B: /S" - command to make it bootable. I got hold on an diagnostic disk image from this site, extracted the contents and transferred them to the bootable 5.25"-floppy.

Still no respons from the drive.

I therefore tried to connect a 3.5"-floppy which I had laying around. The cable interface was very different, as well as the power connection. But there are adapters for everything which I had in a drawer somewhere.

By making a 3.5"-floppy with the diagnostic software, I was able to boot in the setup-program by accessing it directly from MS-DOS and running "ARSTART.BAT" from A:/. I changed the floppy drive to a 3.5" 1.44 MB-drive. Everything seemed to be OK!

I had an idea that if I removed the 20 MB HDD which was mounted next to the floppy drive, I could install a "Compact Flash-to-IDE"-drive and perhaps mount the 5.25"-drive in it's place and use a double-floppy-cable connected to the same floppy-connector on the mother board.

So my next step was to remove the 20 MB HDD and replace it with the CF-adapter. I booted it up and got the 162-error message saying there was a config mismatch. Understandably! So I booted with the setup-disk again and changed the HDD-type to the largest type I could find that worked (type 42 I believe - around 528 MB). After restart I booted with a MS-DOS 6.22-boot disk into command line and used FDISK to format the drive to 528 MB. It's a shame not to be able to use the entire 16 GB CF-card, but it the only one I had laying around. I then installed MS-DOS 6.22 and Windows 3.0 just to check if it would work with this machine. 

Working with Windows is much simpler with a mouse. The Compaq has a serial-port on the back, and I happened to have a Microsoft mouse with a serial connector which I plugged in and used with a standard Microsoft Mouse-driver for DOS and Windows 3.x.

After setup of MS-DOS 6.22 and Windows 3.0 everything worked like a charm on this old device.

I now had an open bay for a 5.25"-device. And I wanted to have both the 3.5" and the 5.25"-floppy drive installed. I didn't have much experience with this from these old devices, or did I know if it would work and if I needed any jumpers to be changed.

So I used my double floppy connector cable together with a power adapter with a split for both molex and mini-molex to connect both floppies to the single floppy connector on the motherboard and shared power source. The floppy cable has connectors for both older and newer floppies, both before and after "the twist" in the cable.

Then I booted it up....and that's when it happened!

601 - Diskette Controller Error

Yup! Something had to come....

The 601 - Diskette Controller Error! An error telling me that there is something wrong with the floppy setup. Basically that I have been experimenting too much without much knowledge of the consequences!

So I looked up a manual online, both for the Compaq Portable II and the Portable III 386/Plus.

I could not find a manual spesifically for the 286-version of the Portable III (I think).

In both manuals the suggestions were to check the cables and drives and eventually replace the Diskette Controller Board.

I checked the cable setup and tried to revert back to the original setup with both the 5.25" as well as the 3.5"-drive and 20 MB HDD. But there was no change, still the same 601 error.

And I couldn't change the setup either, as I needed to boot with the setup disk.

I found a nice site with pictures of the different chips and what they did right here. I combined that page with the manual and some forums around, and figured it could be the controller chip on the mother board as I couldn't find any other physical damage on the board.

So out of options I decided to check eBay for any replacement chip...

D765AC-2

A few Google- and forum-searches later revealed the diskette controller chip to be a D765AC-2.

I decided to buy a new-old-stock chip from a vendor in Germany as this would take the least time for shipment.

After a week it arrived in the mail, and I had previously unsoldered and removed the old chip from the motherboard.

I placed the new replacement chip on the board in hope that this would solve the issue. At first I only placed it the correct way with the pins protruding through the motherboard without soldering, but making sure that the pins were touching the edges of the metallic rings on the holes.

When I booted it up the 601-error still came up. But this time together with the 162-error code. Pressing F1 only gives me the "Non-System disk"-message.

Once again I tried to change the different configurations on the cables connected to the drives, both with single setup and dual setup. Still same error. I even got the error code with no cable installed.

I then changed the direction on the connector on the motherboard, making the direction pin on the cable go the opposite way on how it is supposed to be. This actually removed the 601-error and only gave me the 162-error message. I found this to be odd, as I know that the correct way of connecting the cable was with the direction pin in the correct way.

However, pressing F1 still gave me the "Non-System disk"-message.

What I found to be concerning was that though the spinner on the 5.25"-drive was constantly rotating, there was no indicator light from the drive when pressing F1 or any noise that it was trying to boot from the floppy. The same was for the 3.5"-drive. Perhaps no wonder since the connector on the motherboard was the wrong way, but still odd that the 601-error disappeared.

I then asked a couple of retro PC forums on facebook and Reddit for help. I got some very helpful tips, but unfortunately none of them made the floppy drive try to boot the disk (or even attempt to).

Facebook group Retro PC Gaming - at date 22. august - membership required for link to work.

Reddit group Retro Computing - same date - might require membership for link to work.

I had a different 5.25"-drive encased in a removable drive bay (from Sysgen connected to my IBM) which I removed and mounted on the Compaq to see if there was something wrong with the other drives. Still nothing new...

My next attempt at a solution was to remove the motherboard and carefully soldier the connector in their place.

As I had only soldered components like this a few times before I had the utmost respect to being careful not to damage the board in any way. I don't know if I was careful enough though it looked alright from post-inspection with a magnifier glass.

When I started up the Compaq again, I still got the 601-error. 

1. The only change now was that I got the error code when the floppy cable connected to the motherboard connector was both ways. Previously I didn't get the message when the cable was connected the wrong way only. But this time I got the code in all configurations.

2. The other change was that the D765AC-2-controller chip was NOT getting hot like when it was only placed in the holes without soldering. 

BIOS-chips replacement

After about a month of letting this project sit on the shelf and see if this blog and other posts on Reddit would reveal any solutions, I tried a few different solutions.

One person told me that it might be the BIOS-chips that weren't functioning as the should.

I though that could be worth a try since I didn't have any other options at that point.

Through the forum of www.vcfed.org I found a guy in the UK who could program EPROMS on brand new chips. I found the ROM-images I needed from this site, and asked him if he would take the job. Luckily he did, and a week later I had fresh new chips in the mail. I asked his advice, and he didn't think the BIOS-chips were the problem as the start-up sequence progressed past the RAM-check, but that it couldn't hurt.

As suspected, there were no change in progress after replacing the chips.

However, I now know were to get EPROMs and other ROMs manufactured in case I need replacements! :-)

The solution

Not long after I replaced the EPROMS with no success, I saw this post on Reddit on a completed similar project, and asked if he had had any similar problems.

As it were, he actually had the same issue and also thought the Diskette Controller-chip could have been the issue. It turned out it wasn't, and he had discovered the 5V-line to the floppy drive did not feed any power. He recommended me to test it the 5V-power worked; so I measured the 5V-line and GND, with no indications. 0V! The 12V-line indicated correctly, though!

And that's when I had my epiphany...my WOW!-moment! Finally I was getting somewhere!

I followed his advice and soldered a direct connection between the 5V-connector on the top to the 5V-connector on the floppy drive- and the HDD-power pins.

I started her up, and voila...the 601-error was gone forever!

Final setup

After finally having found and fixed the problem, I could move on and continue with the setup.

I added a math co-processor of the type Intel D80287-8MHz to the available FPU-slot for extra speed on any supported software. This should increase the clock frequency to 20 MHz total for Windows 3.1. But since I don't have more than 640 KB of RAM, I can't install Windows 3.1 as it requires more RAM and also the Extended Memory controller installed, and as far as I know it won't install when there isn't any expanded memory beyond 640 KB... So I intend to find two compatible RAM-chips of more that 500 KB each to increase the RAM sufficiently.

I connected the original 5.25"-floppy drive as BIOS was reset to it's original state.

I had an original DOS 3.30 case with both 3.5"- and 5.25"-floppy disks for booting up to "dos-mode" and being able to read a floppy with the Compaq setup program since I don't have the original bootable disks. That worked like a charm, and I changed the settings to a 1.44" MB floppy drive and a type 42 - 528 MB HDD.

I shut down the computer, swapped the drives with the 3.5" floppy and the Compact Flash-to-IDE-drive and put everything back together again.

And...that feeling when the boot-up go as planned...

Further projects

Now that I have everything up and running, there are a few upgrades I intent to finish eventually.

1. Replacing the keyboard cable as it is brittle and damaged.

2. Installing more than 640 KB RAM in order to install Windows 3.1 and making better use of the math co-processor.

3. Enjoying myself...

A big shout-out to all the people of the internet who assisted me in my project...I owe you!

Humbly yours...the pilot