ibmapc wrote:Anonymous Coward wrote:Does this device support multisync EGA modes like 640x480 and 800x600 etc?
I can't get mine to work with anything above 640x350 using my ATI EGA wonder. I've been meaning to ask retrocanada76, the designer of this device, if the firmware could be modified to support those higher resolutions.
640x480 and 800x600 are on the VGA spectrum. The device does not have memory enough for holding an entire frame. Unless you design a pass-through mode only converting the TTL to analog. But since I don't have one of these and I don't plan buying one I won't bother.
But there is an easier way to make an adapter for these modes, the VGA is 0.7Vpp so if this output is 6 bit like R1R0G1G0B1B0 all you do is to provide each line a 2 resistor in parallel:
R0 : 1500 ohm
R1 : 750 ohm
G0 : 1500 ohm
G1: 750 ohm
B0: 1500 ohm
B1: 750 ohm
The VGA has a 75 ohm impedance: 5V * (75 / (1500 + 75) + 5V * (75 / (750 + 75)) will give you 0.6926Vpp
The H and V sync are TTL on VGA so just connect them direct. This should work beautifully...