...and the answer is...
yes, this is an OLD style monitor adapter. apple (computer) originally used a different connector for their video...where standard vga uses three (3) rows of pins, apple used two (2) rows. some monitor vendors began to include these "dongles" (if you will) so that they could make some headway into the macintosh market. these days, since apple has given up "going it alone" and has started using industry-standard components, these devices are relegated to those of us that still have and/or use older systems.
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my mac collection goes from a 512 fat mac (still looking for a 128) up to a quad g5 along with a few powerbooks, mb, mbp, a few apple //e and gs, and a few windoze systems...all work, all with original system and aplication software discs.