boobee wrote on 2020-08-16, 05:21:

How do i know, before i can run the computer, which bus uses integrated on mobo GD5428, VESA or ISA bus? Hope it's VESA. Riser c […]
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How do i know, before i can run the computer, which bus uses integrated on mobo GD5428, VESA or ISA bus? Hope it's VESA.
Riser card on this machine equipped with ISA slots only. So no way to enjoy (install) VLB video, if integrated is ISA.

ICL ValuePlus DL/66di
mobo: FIC 486-GAC-V

It is most likely (and hopefully) on the Local Bus, but I guess it's not operating in VESA local bus mode (which redefines a few signals for better compatibility with multiple cards), but in native 486DX bus mode. If you have an multimeter (to measure resistance), you can check the configuration strap pins on the CL-GD5428 chip. Bus type is selected using the pins MD30 (pin 98), MD23 (pin 108) and MD21 (pin 110). Probe them with the positive lead on the CL-GD5428 chip and the negative lead anywhere at ground. If the board is installed in a case with the power supply connected to the board, just dump the negative probe into some screw hole. These pins ar configured by placing a resistor (or not) from these pins to ground. The datasheet suggests to use 6.8k Ohm resistors, to be extra-safe use the 200k Range, not the 20k Range, in case the board manufacturer used 22k resistors instead of the recommended 6.8k resistors.

If you can measure (or visually find it by following traces) a resistor between MD30 and ground, but not on the other two pins, the graphic chip operates in 486 local bus mode. If you can measure a resistor between MD21 and ground, but not at the two other pins, the graphics chip operates in VESA local bus mode. If there is no resistor at all, the graphics chip operates in ISA mode.

a bit complex... thx