Hi, I used to use my 520STM+ (a 520STM factory upgraded to 1MB RAM, a UK only thing I believe) on a Philips CM8833 monitor, it would handle both low and medium res without a problem. I know STs can also drive CBM 1701s without a problem. However, unless the monitor output of the STacy is different to the normal ST, it won't drive a CGA monitor. CGA monitors expect TTL RGBI, whereas the ST outputs analogue RGB (albeit at TTL levels, hence the reason for having to install dropper resistors in the RGB lines when driving a normal, non-Atari colour monitor). TTFN - Pete.