FWIW I'm attaching the BIOS that I dumped from the motherboard. Will try the file in my previous post soon.

(edit) the bios from the GW-286CT works in this motherboard, but it still doesn't detect the extended memory. Still testing.
FWIW this motherboard can take flash chips instead of EPROM, I used a Winbond 27C512 instead of the original Microchip 27C512 and it works.

(edit2) even with the new BIOS, no go with either the SIPP memory or the ISA memory cards. 🙁
Just finished going through several memory cards with the testext program, no memory is detected on either.

Damn it. I still can't get it to boot with memory only in the SIPP slots. I even used one of those ISA diagnostic cards which is completely useless, it gives me a few error codes which in the documentation show as "reserved" and which are in fact identical to the codes it displays on a successful boot. The only useful information I get is 3 short beeps at boot. The BIOS is a C&T one, there is no other trademark anywhere - but if it was in fact AMI the beeps would indicate base 64k RAM failure. I don't understand why the motherboard doesn't boot with the SIPP memory (the memory itself is known good; I used 3 different sets of sticks too). There are no jumpers to change from DIP memory to SIPP memory. http://www.lejabeach.com/Biostar/MB-12Series/ … -1212Csipp.html

A while ago I received a 286 board (Essex Electric) that wouldn't boot. Searched the net and found a thread on vcfed. There were some pictures, and based on that I noticed that the SIPPs on mine were installed backwards. There was no notch or any other marking of pin 1 on the motherboard. I see your slots have a notch for pin 1, but maybe worth checking with a multimeter if that's the true orientation.
My board worked right away after flipping the modules, so I guess the pinout is really that fault-tolerant 😀

I had thought about that too, the 30pin SIMM/SIPP does tolerate being inserted the wrong way without dying (Vcc and GND are mirrored in the pinout)
http://pinouts.ru/Memory/Simm30_pinout.shtml . The motherboard does have pins 1 and 30 marked near the SIPP. I also found pictures on the net of this morherboard with memory modules inserted showing the same orientation of the modules.

I also did a test where I inserted the modules backwards on purpose; it didn't make a difference. The RAM still works fine after that (tested in another SIPP motherboard), and the Biostar motherboard also works as before but still boots only with DIP memory, not with SIPP memory.

FWIW I have found a partial solution. It was a composite of several issues:
1. Some of the memory cards I was using I had a poor understanding of the switch setting (due to the manual being poorly written)
2. This motherboard requires parity enabled both on the motherboard and the extended memory cards in order to recognize RAM on them. I had initially parity switched off in the BIOS, but after I switched it on I started making progress.

One problem remains: It still doesn't work with SIPP memory. Even with parity switched on (and of course using parity modules) it still won't boot. It only boots if the DIP sockets are populated, and the SIPP sockets are not.

Hi stamasd,

I got you covered. I just got this board the other day. I have the BIOS like the one pictured in the link, but mine is only version 125D. I would love to get my hands on that newer one.

FWIW, I am running the board exactly as you are describing. It came with 1MB onboard that I removed and replaced it with 4MB of SIMMs. Actually, my board is the SIPP version, but I replaced the SIPP sockets with double SIMM sockets and it is working just fine.

I have a couple of these boards with the newer BIOS versions 127D3 and 129D3. I was going to add them to the 286 bios image collection once my TL866 programmer arrives. I'm not sure how accurate or reliable the NSSI dump is but if you want those in the mean time... I'm not sure I can post attachments or images yet. I'm a new user. I'll give it a try later.