The "BIOS is not installed" message appears when there are no SCSI drives connected.

Set all jumpers in OFF position (default by user manual).
Attach SCSI hard disk.
Run SCSISelect utility by hold CTRL+A while POST and boot.

It says 'Can't locate host adapter' or 'Host adapter configuration error' even with SCSI hard drive or SCSI streamer. And when I run SCSISelect, the utility advices to ensure the card sits well or I set the proper I/O port address.

There was a possibility I have a conflict of two VLB cards so I tried ISA videoadapter and tried moving Adpatec to both VLB ports with the same results. The card looks like it seats well. It runs the card BIOS that does not detect the adapter. What else can be wrong?

Can you take a picture of your 2842VL ? You did try the ECS board with onboard floppy and onboard IDE turned off ?
All the images I have seen of the 2840 or 2842 has 8 DIP switches and just one jumper, not 10 jumpers.
Also those Adaptecs were never tested or confirmed to run on a 40Mhz VLB bus and "Of all the various CPU chips on the market, the Intel 486DX series of CPUs seem to be the most compatible with our adapter." (from Adaptec website archive)
They were designed to be run in the "Master" VLB slot, not a "slave" slot. Some boards have Master/Slave, some have dual Masterslots and a slave slot , etc
if running a DX80, DX120 it may never work unless you change the boards VLB wait states to 1 or more. Also there are known issues with WB cache CPU's and those SCSI cards but not with WT cache. (again from Adaptec web archive)
Have you tried running Debug to directly access the SCSI BIOS ? If similar to 1540 but VLB then debug should get you in no matter the port as you are accessing the BIOS directly (like a MFM/RLL controller)
"At the DOS prompt type debug and press Enter.
Then at the Debug prompt (a hyphen), type g=xxxx:6
where xxxx = first 4 digits of host adapter BIOS address in hex. (D8000h is the default address.)"
It is possible the BIOS is bad or the adapter has a different issue, suggest cleaning all ISA and VLB contacts on it with ISO Alcohol on paper towel...Just thinking out loud 😀

@Horun thanks, I just found the Adaptec notification.

I looked closely one more time and it turned out I have 2482A card with additional WB jumper on it 😀 I removed the jumper and it started!

Adaptec article suggests a lot of different options - disabling cache, disabling Turbo mode while it starts and so on. I also tried VLB delays. And this WB jumper was the last.

How can I check the speed of VLB Bus? My CPU is DX2-66. I suppose they work on the same 33MHz speed while CPU just doubles it internally?

Thank all of you, I spent a day on this beast. Now I need to assemble this monster with my 18GB drive and adaptor 😀

Great you got it working ! with a DX2-66 the VLB bus would be 33Mhz yes. Sorry I should have just linked to that notification but the URL was extremely long and was not sure if it would work proper.
Link for the future https://storage.microsemi.com/en-us/support/_ … ng_aha-2840.htm
I did notice that some 2840 and 2842 had the jumper pads but no jumper pins.

added warning: it may not support drives bigger than 8.4Gb no matter what you do in the scsi bios, is a known issue with even newer 2940U and UW.

https://ask.adaptec.com/app/answers/detail/a_id/906 - and here is my link that has more options to try.

Ther are not many companies that keep their knowledge base articles, FAQs, drivers, manuals etc. from the 90ies still available online up to this date.
This is one reason why I still appreciate and prefer Adaptaec / Microsemi controllers today.

Indeed. Sometimes I have to read Linux kernel sources to get information there 😀