08.02.2014, 12:33 Uhr
|I've recently inherited a Robotron EC1834 computer manufactured ca. 1989, but it has no video card. I've found that ISA slots are quite compatible with EC''s, so I've built an adapter from Robotron's 96-pin connector to 8-bit ISA slot using 1:1 pass-through with outer pins. Unfortunately it doesn't work with any card I've found (tested CGA, VGA and Hercules). Does it work with dedicated Robotron card only?
If I turn EC on, with or without video card (or with only video card), keyboard LEDs go on, then off, and a long then two short beeps can be heard from speaker. Meanwhile keyboard lights quickly flash once, Num lock LED can be toggled then. 8255 port-A shows 10000000, memory seems to be somewhat running (data out in chips toggles, in chips closest to ROMs it changes less frequently than in others.
I've tried different SW1/3 and 4 combinations, no effect.
ROM versions: s721, s722, s716.
Does it need a special graphics card or my mainboard is bad?