Bryan Parkoff wrote: > Mac to VGA Adapter Question > > Altex, Inc in Texas sells Mac to VGA Adapter. I believe that Mac video > port has the same as Apple IIgs video port. Mostly, yes, but they are not identical. The IIgs video port supports the IIgs RGB monitor, and any similar analog RGB monitor which is able to support scan rates compatible with NTSC (15.75 kHz) and has compatible synchronization signals. The Mac video connector uses several pins to identify the monitor which is connected. Early Macs used three pins with combinations of diodes in the plug to identify the monitor. More recent models support the same identification scheme as recent VGA monitors, which involves an I-squared-C protocol communication between the computer and a small chip in the monitor cable (or inside the monitor). The actual video pins on the IIgs and Mac monitor connectors are the same, but Mac monitors (and VGA monitors) have much higher horizontal scan rates (at least 30 kHz), and they aren't able to support the low scan rate of the IIgs. > Do you think that Apple IIgs will be compatible to Mac to VGA Adapter so > it will allow me to view SVGA monitor to Apple IIgs video port through Mac > to VGA Adapter. It won't work by itself. You would also need a devise which doubles the scan frequency, so that the monitor is able to lock onto the video signal. -- David Empson dempson@actrix.gen.nz