TTL RGB ==> PC

On 05/11/2007 12:49, Jules Richardson wrote: It's a pity you didn't ask this yesterday when you were here: I could have shown you my workshop monitor. It's an Acorn AKF53 connected to an ordinary 4-way KVM switch (only the Video part used) to which, in turn, are connected a BBC B's RGB output, a PC's VGA card, an Archimedes, and something else (usually). All work. I can't remember what modes an AKF12 or ADF32 support, but if one of them is similar to my AKF53, that's your choice. If it works for a Beeb, it should work for other machines that have similar RGB outputs. Alexis' idea about the circuit should work too. His surmise about 1V pk-pk for VGA is correct; I've used a similar circuit to do exactly that, and something not too distant to combine all the signals to make composite video (I could have shown you the ISA card for that too, though it only uses the ISA bus to get power). If you need to merge hsync and vsync, a simple XOR gate (1/4 of an LS86, for example) will do well, but often you can get away with just combining them, wire-or style, possibly with a couple of small-signal diodes. Some monitors don't mind the hsync disappearing from the composite signal during the vsync pulse; others prefer it to be present (inverted, if you use an XOR). Have you tried any flat-screen monitors? Some of them are designed to work as TV displays, and will handle horizontal rates in the 15kHz range as well as signals in the VGA (etc) ranges. -- Pete Peter Turnbull Network Manager University of York