Subject: Re: Localtalk interface design ideas
To: Jonathan Stone <>
From: Bill Studenmund <>
List: tech-net
Date: 02/13/1997 19:41:11
> There's no driver support because there's been no reason to support
> the DMA mode until now.  The PCLK runs at 7.3728, which if memory
> serves, can support the link speed used by LocalTalk.

True. The only things to be needed then would be to get the 3.68
MHz clock to the RTxC pin (or I think the TRxC would do too), and
to add buffers on the transmitter. Then you've got a mac serial port!

> If memory serves, cgd argues the scc driver should be taken out
> and ^H^H^^H^H disposed of in an ecologically-sound fashion, but
> that's another story. I don't see glomming such support into the MI
> 8530 driver is going to be a win, though.

While hacking on the mac68k driver to make it fit into the M.I. driver,
I thought about what would be needed to make the M.I. driver work with
the dec setup. From what I saw in the scc docs, the one stickler is that
DTR and RTS seem to be on a different side of the chip than the whole
rest of the tty (they used DTR and RTS on channel a when the transmitter
and receiver were on channel b, or something like that).

So the only places in the M.I. driver which would need hacking would be
the ones which touch those two bits. I think some clever semantics
work could make it work right in the M.I. layer.

Take care,