Macintosh Display Cards 824 & 824 GC: Rev A/B Differences

Why doesn't the ROM upgrade to the Macintosh Display Card 8*24 GC Rev A
allow 16-bit color on the Macintosh 16-inch Color Monitor? What is the
difference between an upgraded Rev A card and the Rev B card?

Also, why doesn't the Macintosh Display Card 8*24 support 16-bit color on
the Macintosh 16-inch Color Monitor?

This article has been archived and is no longer updated by Apple.
Although the ROM upgrade for the Rev A 8*24 GC card allows this card to
work with the Macintosh 16-inch Color Monitor, the ROM version isn't the
only difference between the Rev A and Rev B 8*24 GC cards. The Rev B card
includes a new CLUT/DAC chip that supports a 16-bit color lookup table
that is necessary for 16-bit color support. Because this chip isn't
available on the Rev A card, this card won't support 16-bit color.

Similarly, since the 8*24 card doesn't have a CLUT chip that supports
16-bit color, this card won't provide 16-bit color support. However, just
like the 8*24 GC, you will need to upgrade the ROMs on older versions of
this card if you wish to use a Macintosh 16-inch Color Monitor.

Published Date: Feb 18, 2012