Re: Digital Modems

Brian Elfert (brian@citilink.com)
Wed, 18 Sep 1996 11:30:45 -0500 (CDT)

On Tue, 17 Sep 1996, Joe McGuckin wrote:

> Actually, the Ascend uses a card stuffed with Rockwell *analog* chipsets. So
> does Cisco's AS5200 and the USR Sportster.

The only Sportster that used a Rockwell chipset is the Sportster SI,
which is discontinued. Current products use USR developed technology.

> The USR Courier and the Livingston use a DSP chip to implement the modem in
> *software* (can you say firmware update?). The advantage of this is faster
> turn around times for new feature implementations and bug fixes. If rockwell
> discovers a bug in a critical portion of their chip, they have to spin a new
> revision. Three months would be an optimistic guess for the time involved. Also,
> it's kinda inconvenient to unsolder all those chips from the PC boards.
>
> With a DSP implementation, the vendor distributes a firmware update - that's it.

The Sportsters, both the old and new versions, also implements the modem
in software, but the firmware is not flashable.

The old Sportster design was a near duplicate of the Courier design. It
used the same DSP and the same 80186 CPU. The firmware is different and
is not flash upgradeable.

Brian