Intel PC-BUBBLE Card documentation?

[Eric Smith]

On Thu, Feb 14, 2019 at 2:53 PM Josh via cctalk <cctalk at classiccmp.org>
wrote:

> The empty 40-pin should be an Intel 7224 if the card is using 7114 bubble
> modules, and the 7220 if it's the 7110 bubble modules.
>

Although there is a datasheet for the 7224, I don't think it went into
volume production. It looks like they made the 7225 instead. I'm not sure
what, if any, differences there are between the 7224 and 7225; it might
just be a part number change.

For the 7220 used with Intel 1Mbit bubble devices (7110), one has to be
sure that it's an _Intel_ 7220, usually D7220-1. The NEC μPD7220 is a
graphics chip (equivalent to Intel 82720).