Running the Macintosh II High Resolution Video Card at 512x384?

Ron's Computer Videos

Active Tinkerer
Oct 15, 2021
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Apple's Nubus Macintosh II High Resolution Video Card for the Mac II ***supposedly*** supports 512x384 resolution. I also have a Sony CPD-200sf multisync VGA monitor. I purchased a PTC MAC to VGA Adapter on Amazon which also ***supposedly*** supports 512x384 resolution.

With the card installed in a Quadra 700, for the life of me, I cannot get the Mac to display another other than a 640x480 signal.

I've reset the PRAM multiple times to clear out the last resolution... and it makes no difference.

HELP?