abc wrote on 2020-10-02, 16:23:

1) Is this Hendrix motherboard on photo ?

Yes

abc wrote on 2020-10-02, 16:23:

2) I have upgraded video memory from 1 to 2MB by two NEC 512KB chips. Can I use 1MB chips to get 3MB total ?

No

abc wrote on 2020-10-02, 16:23:

3) I did a search for a manual but without success. Someone have and could link or upload ?

https://arvutimuuseum.ee/th99/m/I-L/32246.htm

abc wrote on 2020-10-02, 16:23:

4) Dallas chip is refurbished but I have mixed with other chips and couldn't find original. Some booted with password, some hangs on booting to A: and others have problems hanging on when Speedsys is launched on Year 2000 bug test. Strange that not BIOS chip holds password but RTC chip. It is normal ? Can I clear it with jumpers on that mobo ? I could try it but without manual it is hard.

Use DS12887 module (or compatible). DALLAS is chip is not a BIOS chips (thats the one with sticker next to ISA slots). Dallas module combines CMOS storagage and RTC clock. That's normal.

The J5A1 jumper disables just the password. The J5A2 clears the complete CMOS (supposing DS12887 chip is installed).

Thank you for the answers. I have put in DS12887A and now all is OK. Speedsys doesn't hangs on 2000Year Bug test. I will try clear passwords on the rest and turn on Turbo mode with help from manual.