Have you got one of these ISA POST testing cards? You might want to get one of these. They also come as PCI version.

First try to re-seat the HD146818 chip (when pulling it check if some pins are corroded). If that doesn't work try one from another board (a DS1287 works too iirc). If it still doesn't work some traces may have been damaged by the battery. You can try to clean it then.

h-a-l-9000, you are a super star. A retro ninja. Thanks! 😁 I replaced the HD146818 chip with a Dallas RTC code DS12887, and I no longer see that BIOS POST error message. Instead, I am able to navigate the BIOS set up area. Awesome. I will mess about with this board, and see what it can do. Please note that I tried to reseat the HD146818 chip, but that didn't solve this problem. Perhaps the chip has died? Perhaps the legs are corroded, although they looked OK.

Mau1wurf1977, I do have a BIOS POST test analyzer card. Somewhere. 😉 😦

Now you don't even need the batteries...

Nice board. If only it didn't have the cpu soldered.... 😀

What do you want to replace a 286-16 with? A possibly rare 286-20?

Exactly! I've got just one spare board to play with, but it's like that.... Is the 286-20 so rare? I didn't know. Last year I won an ebay auction having 4 386dx/16, one 386dx-25, and a Harris 286-20 for about 15-20$.

Markk wrote:

Exactly! I've got just one spare board to play with, but it's like that.... Is the 286-20 so rare? I didn't know. Last year I won an ebay auction having 4 386dx/16, one 386dx-25, and a Harris 286-20 for about 15-20$.

It isn't as much the CPU's, as it is getting a 286 motherboard that will run at 20mhz where you're going to spend the most money. The CPU's are rare, but the motherboards are even rarer.

Very unfortunately, my luck with this board has taken a "wrong turning". 😉 I decided to continue testing the board, to see what it could do. Very quickly, I realised that something was wrong. After successfully entering some basic set up details inside the BIOS set up area, the BIOS POST memory count freezes. Usually, it freezes on 64Kb. Sometimes it will get higher, and then freeze. I have tried various memory configurations on the mobo. For example - I have removed all of the little memory chips on the board, and installed four 1MB SIMMs. This should work, but it doesn't help with this current problem.

Very luckily, I spotted an auction on ebay for a used HD146818 chip. It's identical to the "clock chip" that I removed, and replaced with a Dallas RTC. BTW, I have also tried 2 Dallas RTCs, and one ODIN RTC. All 3 RTCs do not allow me to boot up this mobo successfully. There is an unfortunate side effect with this current problem that I having with the mobo. When the memory count freezes (as seen in the photo below), I cannot get back in to the BIOS set up area. I am completely locked out of it. The only way to proceed, is to remove the Dallas RTC unit, and replace it with another!

Just once, out of about a dozen boot up attempts, the boot up sequence worked, and DOS 6 was booting OK from a floppy diskette in drive A:. But it froze when it looked for the CD-ROM drive, but this may be because I do not have any optical drive present. However, I would expect the boot up sequence to skip past this stage. Perhaps a 286 can't cope with DOS looking for a CD-ROM during its boot up sequence?

sliderider wrote:

It isn't as much the CPU's, as it is getting a 286 motherboard that will run at 20mhz where you're going to spend the most money. The CPU's are rare, but the motherboards are even rarer.

I thought that If I had a fairly late 286 board, with a HT chipset like that, which supports a 16MHz cpu, would be fine at 20MHz by changing the crystal. I have an identical board as the one in my 286 pc, but I was thinking I should avoid modifying anything on that, and just keep it for spare. The CPU can be changed, but the crystal is soldered on the board. Perhaps it's not a big deal to desolder it, and attach a socket for a crystal.

RG100, if it worked fine before you changed something in the BIOS setup, then you should remove the dallas chip and the batteries. Leave it sometime, and then put them back on. It should then have it's original settings.

edit:

retro games 100 wrote:

Just once, out of about a dozen boot up attempts, the boot up sequence worked, and DOS 6 was booting OK from a floppy diskette in drive A:. But it froze when it looked for the CD-ROM drive, but this may be because I do not have any optical drive present. However, I would expect the boot up sequence to skip past this stage. Perhaps a 286 can't cope with DOS looking for a CD-ROM during its boot up sequence?

I think my 386 used to do that also. If you manage to boot again, press F8 when it says Starting MS-Dos ....., and avoid loading the cd-rom driver.

Just to be sure, the battery you removed was rated for the same voltage as the batteries you're using now?
I had a similar issue with another (much more modern) board once. It would either successfully boot, or it would freeze during the RAM count. Sometimes it even froze hard when inside the BIOS itself.
A BIOS update didn't fix this, not did swapping memory around.
Another strange thing was that I was totally unable to load any kind of Windows onto that thing, it would generate somekind of error, kinda as if the system was sticking up it's middle finger or something 😜
What was especially weird with this board is, I could move an existing 9x installation to it and it would work perfectly fine?? At least afaicr.

Never figured out what it's problem was, but I ended up redesignating that board for testing CPU's -_-

Oh, that's right! Check the voltage of the batteries. On my 286, on which the board is similar, 2 AAs are enough. I have them for over a year up to now, and they hold the date/time very accurately.

With the DS12887 he plugged in batteries are not required at all (it is included in the DS12887). Somehow I doubt the freeze has to do with the RTC chip. But then maybe it is too modern for the BIOS to handle.

Unfortunately, I am not having any success with the Dallas RTC. I have experimented with various mobo jumper settings, just in case something is incorrectly configured on the mobo, but this hasn't fixed the problem.

As I have ordered a replacement HD146818 chip, I will have to go back to using an external battery. I spotted an auction on ebay for various sized battery holders: 2, 3, and 4 AA battery holder packs. My current 3 AA battery holder is not very good, so I'll buy this item, and then try the 2 AA battery holder pack. Thanks.

retro games 100 wrote:

Unfortunately, I am not having any success with the Dallas RTC. I have experimented with various mobo jumper settings, just in case something is incorrectly configured on the mobo, but this hasn't fixed the problem.

As I have ordered a replacement HD146818 chip, I will have to go back to using an external battery. I spotted an auction on ebay for various sized battery holders: 2, 3, and 4 AA battery holder packs. My current 3 AA battery holder is not very good, so I'll buy this item, and then try the 2 AA battery holder pack. Thanks.

Care to post or PM a link? I'm still in the market for purchasing a couple if I can find them for +++ cheap 😁

If you type in
aa battery holder
in to ebay, hundreds of results are returned.

retro games 100 wrote:

If you type in
aa battery holder
in to ebay, hundreds of results are returned.

Doh!!

It's only after reading your post that I remembered I asked you the exact same thing about a month ago! 😅

Tetrium wrote:

retro games 100 wrote:

If you type in
aa battery holder
in to ebay, hundreds of results are returned.

Doh!!

It's only after reading your post that I remembered I asked you the exact same thing about a month ago! 😅

It was several months ago, I think. 🤣

I've just modified my spare 286 board! It had originally a Siemens 286/16.

I removed the cpu, and installed my Harris 20MHz one. It worked of course, but it still run at 16MHz.

Then I took my soldering iron and removed the 32MHz crystal. I broke one of it's four legs, but never mind. I put a crystal socket I had from a broken board, and then tried a 40MHz crystal. It works fine, and it's counting the memory much faster.

In general it feels a lot faster than before. Then I tried to overclock it, by placing a 50MHz crystal, but I couldn't achieve that for more than a couple of seconds...

Now, what's really cool... The cpu! The other 12-16MHz 286s from intel-siemens-amd I've seen, get really hot. I can't touch them after of 5minuts of use. That 20MHz Harris, is a lot cooler. It reminds me a 386sx-25 I have.

I also tried an 8MHz Intel 287 I've got. It also runs at 10MHz, but at 12 the system hangs. This one, gets extremely hot, though. Even at the stock speed of 8MHz....