Early Apple displays don't use the same scan frequencies as PCs did, so many multi-sync monitors don't work. A few which were compatible with the IBM PGA card (anyone remember the Professional Graphics Adapter?) would stretch far enough to cover Apple's Toby and other cards. Most LCDs are too new for the TFB and PCs' CGA signals. What Apple never documented is the Toby Frame Buffer could output video at NTSC RGB rates, so with an RGB to composite adapter, you could use a TV for display. If you were lucky enough to have an Apple II RGB monitor, you could use it with your Mac II. There was a shortage of the Trinitron monitors when the Mac II first came out, and I used my Apple II monitor on my Mac II for 4 months until I got one of the Apple High Resolution Color Monitors.