The Apple Serial NB Card (820-0264-B) is a 12" NuBus card that will add four standard RS-232-C ports or two higher speed V.35 ports, plus two RS-232-C ports to any Macintosh with NuBus slots. Two cables were made for the card. The first has a single db-62 connector that splits into four db-25 serial connectors, while the other provides one V.35 port and one RS-232-C port. When using the 4-port cable two ports operate at a maximum data rate of 64 Kbit/second, while the other two operate at a maximum of 19.2 Kbit/second. The card was generally used on conjunction with the Apple Remote Access kit to give a server a pool of four modems for remote logins. As far as I know, no driver is needed, when installed in a system the additional ports will be accessible from any program that uses the Macintosh communications toolbox.

Being a Macintosh Coprocessor Platform card, the Apple Serial NB Card is equipped with a full 68000 processor running at 10 MHz, 512 KB of 70ns DRAM and its own ROM.

As with all MCP cards the memory can be expanded to 2.5 MB.