It's been a long time since I last put together a coax board uisng a DP8392
transceiver, but as I recall the 8392 needed relatively few external
devices. Its purpose, however, was to drive the coax. I don't believe
there's any need for it in a TP application.
In the classic ethernet/thinnet board design, there was a controller, e.g.
AMD 7990, a modulator/demodulator, e.g. AMD 7992, often with the digital pll
right in it, and a coax driver like the 8392, but, in AMD's case it was
another device with more pins and more external parts.. The
modulator/demodulator drove the AUI outputs, OR, if jumpered appropriately,
drove the DP8392. The DP8392 was also the most costly of the three or four
popular coax drivers, (AMD, Intel, National, and SEEQ) but it was worth it
because of its smaller package size and need for fewer external components.
If the board had an RJ45, and also had the coax connector, it was probably
jumperable, with a dip shunt in some cases, and a 3 or 4 row pin field with
shorting plugs. In some cases, the AUI connector could be adapted to RJ45
with a really small adapter. The adapter to COAX was somewhat larger.
Dick
----- Original Message -----
From: "Tony Duell" <ard_at_p850ug1.demon.co.uk>
To: <classiccmp_at_classiccmp.org>
Sent: Thursday, November 23, 2000 7:23 PM
Subject: Re: 10base2 / 10baseT (again)
> >
> > OK, next question.
> >
> > I've acquired a few Asante FriendlyNet Thin Adaptors. These are little
>
> [...]
>
> > Inside is a standard 5V-9V DC-DC converter, a standard ethernet
3-section
> > transformer, and a perfectly ordinary DP8392 ethernet transceiver IC and
> > the usual discrete components (diode, a few resistors, etc) I associate
> > with an ethernet coax driver. So on the face of it, it looks like a
> > line-powered 10baseT to 10base2 converter. Oh yes, one other thing: the
>
> To me, it sounds more like a 10base2 transceiver with an RJ45 connector
> for the AUI interface. There's not enough electronics there for it to be
> a 10baseT - 10based2 converter.
>
> Now why anyone would use a RJ45 in place of the standard DA15 I don't
> know, but certain companies are well-known for deliberately changing
> standards for no good reason.
>
> It sounds simple enough to trace out the schematic in about 10 minutes. I
> wonder how it compares to the standard 8392 application?
>
> -tony
>
>
Received on Thu Nov 23 2000 - 23:35:32 GMT