Ehh I see the pic is sideways.. When I say 'top' I mean 'right' I guess 😉

MaTi wrote on 2020-10-12, 15:18:

Hi all,

Can someone advise me on which brand/model this board is?

Id like to see if I can find a manual..

Take a look on that sticker 😉

It's a Hedaka HED-988

Here are the jumper settings:
http://www.uncreativelabs.de/th99/m/E-H/31353.htm

And/or, alternatively, I have some questions on things Id like to do:

1) The battery has leaked.. I will replace it. However, next to the battery I see four pins. Are these indeed for an external batttery?
Alternatively I can solder it onto the current place of the battery

JP5 is for an external battery.

Note that the external battery connector does NOT charge the battery, but the onboard battery is charged. So make sure you connect the right type (rechargeable vs non-rechargeable) in the right place.

2) Can someone please educate me on those two rows of pins at the top? What are those?

Those are SIPP slots, for SIPP memory modules. SIPPs are electrically identical to 30p SIMMs, and you can indeed make one from the other by adding or removing pins.

3) Below that there are chips and some empty sockets. Is that the RAM for a 286? Can I upgrade the amount by buying anything for the remaining 8 sockets?
What should I buy? Right now the pc mentions 2MB ram on boot.

The extra sockets are smaller than the regular ones and are for parity (which is now not installed/enabled). You currently have 16 1Mb chips, which is the max you can install onboard. According to the TH'99 entry you can only get more (4MB) by removing the DIP RAM and installing 4 1MB SIPPs.

4) Below that there is an empty socket. What could that be for? Any ideas?

80287(XL) co-processor.

By the way, take a look at your processor - Harris 25MHz. This is the ultimate 286 motherboard with the fastest 286 CPU on it. I'd start looking for 4x 1MB SIPP for it 😉

Might be a challenge to find a co-processor that would work in here, although I heard rumours that some fast boards could run them async at ISA bus speed, in which case any 287 or 287XL rated for 10MHz would work.
Just checked those jumper settings and you can do OSC/1 and OSC/3. With the latter you'd be running the co-pro at 8.33MHz, nicely in spec for the 10MHz versions. Or you can add a second oscillator at OSC1 and let it run at exactly 10MHz - or 12.5MHz if using 287XL

Note that SimCity, ancient versions of AutoCAD and Lotus 123 are about the only applications that would actually use the co-processor, so it's hardly a must-have upgrade.

This must be your board http://www.win3x.org/uh19/motherboard/show/2821
(It should answer for "1)")

2) "pins" = 30 pin sipp memory connector. It didn't last long, it's been replaced with 30 pin simm. You can mod your motherboard to support simm memory slot (the pinout is exactly the same and your board seems capable of fitting simm slots)

3) I think these are for parity. You won't be able to upgrade your ram's size with them. But you can use 2) for that 😀

4) it's a 287 math coprocessor socket. It's not very useful for stuff other than spreadsheets or CAD programs.

Edit :
Ah dionb was faster (you should use uh19 instead of uncreative labs 😉 )

By the way can you backup the bios for me please ? I'll add it to the uh19 page. I'm also going to add your photo there ^^

Btw, regarding those SIPPs, you can buy 30p SIMM slots and use them as adapter to add common-as-muck 30p SIMMs to those SIPP slots:
https://au.rs-online.com/web/p/memory-sockets/3789419/

See: http://sbfmdrv.blogspot.com/2016/01/using-sim … s-as-sipps.html

And yes, will bookmark uh19 😀

Awesome guys.. Thanks for the great help and quick feedback! Will read into this all later tonight 😀

Once I have it up and running again, I am happy to backup the bios for you.
Which tool should I use for that?

Also, I just bought 4 1mb SIMMs and I think I found a source who can deliver me 4 of those adapters (great tip, thanks!)..

Another noob question, sorry.. once those get in, according to the manual I should unpopulate the DIPs. Can I just pull these out?

I guess I'll skip on the 287, due to limited support and relatively high prices online.
Ther CPU is the 20Mhz version it seems btw, not the 25 Mhz version.. Also, that's not supported on the board according to the manual..

MaTi wrote on 2020-10-13, 00:04:

Once I have it up and running again, I am happy to backup the bios for you. Which tool should I use for that? […]
Show full quote

Once I have it up and running again, I am happy to backup the bios for you.
Which tool should I use for that?

Also, I just bought 4 1mb SIMMs and I think I found a source who can deliver me 4 of those adapters (great tip, thanks!)..

Another noob question, sorry.. once those get in, according to the manual I should unpopulate the DIPs. Can I just pull these out?

I guess I'll skip on the 287, due to limited support and relatively high prices online.
Ther CPU is the 20Mhz version it seems btw, not the 25 Mhz version.. Also, that's not supported on the board according to the manual..

Yes you should pull the DIPS before trying the SIPPS>SIMMS.
Yes you would want a Intel 287 XL or ITT 287 that can handle 12Mhz or better if you want it be the best 287, and they are not cheap.
The 286 CPU max speed is not an issue ! Have a Harris 20Mhz running on a 16Mhz only 286 board and works great (and runs cooler than the 16Mhz AMD it replaced), as long as the CPU is rated at or above the boards clock speed you are good !

Use this tool to backup your bios https://www.pcorner.com/download?filename=Vsf … xf2fP9xSz6hY%3D

Stupid quick question.. jp5 has 4 legs, my battery has 2. Which pins are + and -?

MaTi wrote on 2020-10-13, 15:30:

Stupid quick question.. jp5 has 4 legs, my battery has 2. Which pins are + and -?

The outer two. - has continuity to ground.

If you do decide to remove the DIP memory you should hang on to it, or sell it. That stuff has become fairly scarce, especially 70ns.

Just because the CPU installed is fast doesn't mean the board is actually rated for that speed, or is even running it that fast. Need to check the oscillator and see if it is 2x the CPU speed

Well according to UH19, which has for source Microhouse Technical Library, it is rated for 20MHz. If I knew which chipset this board uses, it may actually help figuring out what this board is capable of 😀

So, I successfully took off the battery and replaced it.
Also, I replaced the old 40MB HDD with a 256MB compact flash card.

I managed to boot from floppy and successfully installed MSDOS 6.22.
However, once finished it says it completed and wants me to reboot the machine.
When I do so, after post, it comes to the point where it should boot from the CF.
All it does however, is showing a blinking cursus in the upperleft corner.. Then nothing..

When I boot from a floppy it works and I can browse/copy/whatever to the CF card (c:).
Also, FDISK confirms the partition is active and all files it needs to boot are there indeed.

Anyone any ideas?
Thanks! 😀

Deksor wrote on 2020-10-13, 05:21:

Use this tool to backup your bios https://www.pcorner.com/download?filename=Vsf … xf2fP9xSz6hY%3D

Id be happy to do so, but before I can download I need to sign up.
Trying to use FB or Google does not work ("There has been a critical error on your website.") and signing up manually doesn't work either, the confirmation email never gets sent it seems..
Can you upload it to wetransfer or anything so I can download it perhaps?

I can give you another source, but I don't have the time for that right now. iirc you can find it on vcfed.

MaTi wrote on 2020-10-14, 08:27:

When I do so, after post, it comes to the point where it should boot from the CF. All it does however, is showing a blinking cu […]
Show full quote

When I do so, after post, it comes to the point where it should boot from the CF.
All it does however, is showing a blinking cursus in the upperleft corner.. Then nothing..

When I boot from a floppy it works and I can browse/copy/whatever to the CF card (c:).
Also, FDISK confirms the partition is active and all files it needs to boot are there indeed.

I don't know whether MS-DOS sets up a proper x86 MBR when you install it. Try FDISK /MBR to embed the code into the partition table that looks up the active partition and starts the operating system from that partition.

Thats a good one! Gonna try tonight. Thanks!

mkarcher wrote on 2020-10-14, 11:37:

MaTi wrote on 2020-10-14, 08:27:

When I do so, after post, it comes to the point where it should boot from the CF. All it does however, is showing a blinking cu […]
Show full quote

When I do so, after post, it comes to the point where it should boot from the CF.
All it does however, is showing a blinking cursus in the upperleft corner.. Then nothing..

When I boot from a floppy it works and I can browse/copy/whatever to the CF card (c:).
Also, FDISK confirms the partition is active and all files it needs to boot are there indeed.

I don't know whether MS-DOS sets up a proper x86 MBR when you install it. Try FDISK /MBR to embed the code into the partition table that looks up the active partition and starts the operating system from that partition.

That did the trick, awesome!
Could/should have come with it myself, but it had been wayyy too long ago I guess 😀

Here's the program ^^

(use ROMSAVAT.EXE)