Resurrecting x286 PC AT clone system

[eskwadrat]

Back in late 80's my parents bought me my 1st PC. It was an AT close based on AMD 80286 MCU running 16MHz clock with 256kB Paradise EGA, 1MB on board RAM, 40MB WD HDD and Hyundai full EGA monitor. That PC is long gone, I think I sold it around 1990 for $100 to someone.

Now, almost 25 years later I am trying to recreate it. So far it is going good, I was able to import from Europe an AT motherboard with 16MHz version of 80286 very similar to one I originally had with exception of being later model with SIMM sockets instead of SIP with bank of DIP based 1MB RAM.



It is based on VLSI chip from Headland Technology. I was wondering if anyone of you recognizes this motherboard and have copy of manual for it. There is not much jumpers to be set but I always try to backup my projects with as much documentation as possible. Unfortunately this board is missing manual so your help is mostly appreciated.

Here is a link to supersized image, feel free to take a look
HEADLAND_x286-16

I enlarged the chipset and MCU section below. Thanks for your help in advance. I will be posting my progress in rebuilding entire system documenting every step with pictures.

[/img]

[iulianv]

I couldn't find any reference to your exact board, but there aren't many jumpers on Headland-based 286 boards, and yours has even fewer than most of them.

Besides the obvious / labeled ones (external battery, turbo, speaker, and so on), I see two more in your photo:

- the one next to the FPU socket most likely controls the FPU frequency (either in sync with the CPU (which I interpret as 2/3 of the CPU frequency, so on my very similar board a 10MHz FPU is running happily with the 16MHz CPU), or in sync with the oscillator in the socket nearby (which is missing on your board)); throw in a FPU there and see which jumper setting (1-2 or 2-3) allows the board to POST...

- JP3 in the memory area could either select between color / monochrome monitor, or between parity check enabled / disabled (in which case the same hint above applies - make sure there are no RAM parity chips installed and see which jumper setting works)

[i440bx]

Nice

I have also a Intel 286 CLCC full size AT Board running. The problem with unknown Jumpersettings i have too, but my board is running with the actual settings.

Do you have a graphics card wich is accepted by the board? I tryd 7 or 8 ISA ones befor i got a post screen

[eskwadrat]

It's been a while but I have been just waiting for components for my x286 PC.
Finally arrived:
- Paradise PVGA 16-bit ISA (used eBay)
- Paradise EGA 8-bit ISA (used eBay)
- DTC 2280-E I/O IDE controller 16-bit ISA (new Amazon)
- Teac 5.25 Floppy Drive (used eBay)
- Panasonic 3.5 Floppy Drive (new eBay)
- PC AT style desktop case SCC Technology (vintage eBay)
- Classic "clicky" 104-key Keyboard (new eBay)
- new GP 3.6V BIOS battery to replace old one that was not charging anymore (new eBay)
- misc. cables (eBay)

First thing I did was to replace old BIOS battery. New one finally allowed BIOS to remember the time/date and BIOS settings.



When PC case arrived, I found included power supply working great (all voltages checked!) but the fan is very noisy. Quick search on Amazon and replacement fan arrived quick. Replacement was pretty easy but required removal of main PCB. Replaced, quite like a charm. Checked!

The old vintage PC AT style case happen to have misaligned 2nd row of motherboard stand-off slots. These were fitted with modified mushroom stand-offs where I clipped bottom snap. Worked great. Motherboard was fitted properly and screwed on the I/O side which ensures it stability during operation and transport.

One of my favorite items that arrived is clicky keyboard. It is identical to the one I used in the past. It is solid, feels and works great. Rare find on eBay in NOS condition.



I was not able to use EGA card I received, still have a hard time to find EGA monitor that would be in good condition and would support full EGA including 640x350 resolution. Prices found on the net are either outrageous mostly because these monitors are hunted by CNC machine users who suffer from a lack of knowledge that would allow them to replace old burnt monitor with VGA. I still hunt for EGA monitor. If anyone have something to sell, send me PM.

So I installed Paradise VGA card for now and it works great with my Samsung Syncmaster 930B LCD. Hopefully I can add EGA card and add 2nd long waiting EGA monitor. My dream models are either original Hyundai EGA (super rare), IBM5154 or TUV EGA (rare).

[eskwadrat]

Amazingly I was able to purchase brand new 16-bit ISA I/O adapter:
LPT+2xRS232+Game+2xIDE+2xFloppy. Found it on Amazon, works great so far.



Additional Molex 4-pin to 3.5 inch power cable adapter was necessary to hook up 3.5 floppy drive that I wanted to use to boot the machine to partition and format my 15-yrs old WD 850MB HDD. Having 5.25 drive but no diskettes, I was forced to use 3.5 inch floppy which I created using one my old DOS/XP machines.



Last thing was to install math cooprocessor 80287. This one arrived from Russia(!). It is 10MHz version. Installed in empty socket did not show on BIOS boot menu. The adjacent JP1 jumper had to be set properly so I tried lower position, where 287 stayed still not recognized. Upper position cause BIOS to

WAIT.....


during the boot forever, I suspect the adjacent crystal oscillator (OSC1) is not fitted so the main CPU waits for MPU response but without clock feed, never gets it. So I need to get an oscillator which should not be hard having Digikey or eBay at my disposal. I only wonder whether crystal frequency should match MPU rating (10MHz) or should it be half of main CPU clock frequency (8MHz). I plan to order both and try.

[eskwadrat]

Exact configuration as seen on my 1st PC AT clone. Nice



At this point one thing that bothers me is to find out if MPU works actually or is it just bad part. Will find out once I get oscillator in my hand.
I also wish I had a description for the JP1 jumper to find out why lower position does not make any difference from not being fitted at all where in both cases MPU is not recognized by BIOS.

Does anyone have experience with fitting x287 MPU on similar motherboards where JP1 selector is present? See picture below.
I appreciate your reply.



To be continued!

[eskwadrat]

I have just checked connections on JP1. Upper pin is connected to output of OSC1 pin 8. Middle pin is connected to 80C287 MPU clock (pin 32). Not sure where lower JP1 pin is connected to, without a scope it is hard to find out.

Anyway, 8MHz oscillator should work and I look forward to test it. Will also test 10MHz. Parts are on the way...

[Glory_Cloud]

I am enjoying experiencing your journey with you.

I may have an IBM 5154 EGA or it's a 5153 CGA color monitor
at the shop. I will have to check and see if it powers on though.

Where are you located in the US? Shipping can be costly but
it should fit into an 18x18x18 or worst case a 20x20x20 box.

[eskwadrat]

Thanks! Please check PM.

[eskwadrat]

The 10MHz oscillator installed on free socket finally allowed MPU being detected by BIOS so I could activate it. So on this end we got everything covered.




The real challenge came when I tried to connect my old 850MHz Caviar HDD. Although the operation seemed to be trivial, it wasn't. The re-partitioned and formatted under DOS 6.2 disk did not want to boot on this machine. It was booting well on my other PC with motherboard just few years old.

After several hours of checking and re-checking with good old known tools like DOS Norton DiskDoctor & DiskEdit which were showing everything to be ok, I finally came to conclusion that is has to be related to IDE. And it was.

The old pre-1994 x286 motherboards allowed IDE with 22-bit addressing which by the way limits disk size to 504MB. My disk was 850MB and it was partitioned and formatted using LBA addressing available for my new PCB motherboard that I used to prepare HDD. So in order to prep disk for old 22-bit IDE, I had to partition and format it under old standard to make it compatible. The side effect of this was of course shrinked usable disk size of 504MB but my resurrected x286 finally booted just like I wanted.



There are couple of items either waiting to be received or installed in next step. One of them is long waiting EGA monitor (currently have VGA card installed) and old fashioned SoundBlaster ISA sound card.

Both of these are coming next.
My x286 system finally gets the shape I wanted. Isn't it a beauty?

[Thandor]

Looks neat! Nice little baby-AT motherboard you have there. Watch out with the CMOS battery however. I once replaced it too but it started leaking again after a few months ... and the battery was brand new!

Didn't it run with MS-DOS 5.0 originally? And where is the 5,25" floppy disk?