Does anyone know how to convert a video out signal into a signal usable by a CGA monitor (RGB + H and V sync)?
If your CGA monitor is TTL, then it may not be possible, at least not without modifications to the monitor. You need to convert from NTSC to RGB. There are single chips (with a few external components) solutions to this. Try Sony, Philips/Signetics, and Analog Devices (I think) as well as others. These take NTSC (or PAL) and output RGB and sync. CGA is not analog (continuous range of video values). It is TTL with Red, Green, and Blue signals as well as a separate Intensity signal. Unless your CGA monitor can take analog video (.7 V p-p) inputs, you will still only be able to get 8 or 16 colors – not a normal TV picture. (And even for that, you will need external circuitry to convert the analog output of the decoder chip to TTL.) However, some CGA monitors have internal NTSC composite inputs and in that case, it is simply a matter of flipping the appropriate switch.
