Using a 1M RAM card in 48GX slot 1

[BruceH]

No is the short answer.

Looking at the pixel display signals using an oscilloscope, there is quite a lot of glitchy noise so an all blank (all pixels off) screen isn't an all zero voltage signal and, vice versa, an all black (all pixels on) screen doesn't give a clean all +ve signal.

   

The above shows the display for an all blank screen (blank PICT, no menu, just the cursor cross-hairs showing). The top line (blue) is the 'new row of pixels' trigger pulse while the bottom line (yellow) is the row of pixels for one half of the screen. The right hand pulse are the pixels for (one row of) the cross-hairs cursor but I don't know what the half-voltage left hand spike is. It's there all the time so if a glitch then a pretty stable one. Perhaps another timing signal.

Whatever it is, it means that an 'all off' display is not clean enough to attempt to drive a RAM switching card.