[99797] in RedHat Linux List
Re: "Winmodems" (Support in Linux)
daemon@ATHENA.MIT.EDU (Ramon Gandia)
Tue Nov 17 01:33:14 1998
Date: Mon, 16 Nov 1998 21:27:34 -0900
From: Ramon Gandia <rfg@nook.net>
To: dfox@belvdere.vip.best.com, redhat-list@redhat.com
Resent-From: redhat-list@redhat.com
Reply-To: redhat-list@redhat.com
"David E. Fox" wrote:
>
> Agreed, for the most part. The particular internal modem I've
> been using for a couple of years now (a USR Sportster 33.6) has
> its own UARTS, and for good reason -- at least on the system
> I used to run it on (PB) before I upgraded. The PB only had the
> cheaper UARTs (i.e., not the 16550) and worse, they were
> soldered on to the main board.
>
> So in that particular instance it made sense to get a new
> internal modem, since it had the newer 16550A UARTS with the
> bigger buffers.
Unless I am blind, I do not see a 16550A UART on the Sportster
Modem. It has an ASIC chip that takes the ISA bus data and
puts it right on the modem's DSP. The ASIC chip acts like a
16550A as far as the computer is concerned, but its a simulation
only. This is the case with MOST internal modems. The externals
do need a REAL 16550 since they communicate over a serial line.
The UART converts serial data to parallel data. In the case of
the internal modem, the ISA already has parallel data. They just
use the same registers/io port/irq of a serial device for the
sake of using a serial driver (serial.vxd in the case of Win95).
--
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285 West First Avenue rfg@nook.net
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