For those who want to roll their own, here are the particulars on the
V.42bis upgrade for the USR HST and Dual Standard modems...

1) You will need to download USR42BIS.ZIP from the database and use that
   to program a 27C512 Rom.
2) You will need to purchase a Sony CXK58257P-12L (or equivalent) Ram chip.
3) Install the Rom in the Supervisor (SUP) socket.
4) Install the Ram in the Ram socket.
5) Make up two 3 pin jumpers for P9 and P10 with pins 1 and 2 jumpered
on one and pins 2 and 3 jumpered on the other.  Connect the vacant pin 1
on the one to the vacant pin 3 on the other with a jumper wire.
6) Remove the jumpers on P9 and P10.
7) Install the jumper with pins 1 and 2 connected together on P9.
8) Connect the jumper with pins 2 and 3 connected together on P10.

That's it!