AT&T Co’s Microelectronics has announced its entrant in the
Ethernet and 10Base-T integrated chipset race. Last July,
National Semiconductor Corp announced a similar product
which combined the network interface controller,
encoder-decoder and tranceiver onto a single chip. Standard
Microsystems Corp is developing something similar, based on
technology it bought from Western Digital Corp and Chips &
Technologies Inc is about to start shipping a combined Token
Ring and Ethernet chip set.

AT&T’s design has a pair of chips imnplemented in CMOS
technology.

One chip, the T7231 LANpacer Controller, integrates the
local network controller, XT and AT interface logic, memory
arbitration and bus transceivers. It supports shared memory
and automatically senses whether it is plugged into an 8-bit
or 16-bit slot.

The other chip, the T7213 Dual Interface Station Chip –
DISC, integrates the physical layer media interface and
encoder-decoder, and automatically chooses Ethernet or
10Base-T twisted-pair wire connections as appropriate.

The T7231 LANpacer also includes the glue logic needed to
interface it with shared memory in MS-DOS personal computers
and has space for up to 64Kb of shared 16-bit RAM (a similar
amount of 8-bit ROM or EPROM). When you order quantities of
10,000 or more, the pair of devices is priced at under $30
when they are purchased together and are out now.


I could not find a datasheet for the T7213  but I did find
information that the SparkStations from that erra,  e.g.
the SparkStation 10 also used the T7213 at their physical
layer.  It's clear from the Sun technical data on bitsaver
that the custom chip that the T7213 plugs into on the
SparkStation that pin #9 on the T7213 tells the T7213
whether or not to use its TP Enet port or its AUI Enet port
(which goes to ThinNet on the NeXT).