For future lazyweb searches, from disassembly: OpenStep 4.2 Patch 4's VBE20DisplayDriver VESA/VBE 2.0 display driver supports 8, 15, 16, and 32 bpp modes, but for the 16-bit modes it will prune RGB565 - the driver expects RGBX5551 where X is a reserve bit.
9 days ago