Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!munnari.oz.au!metro!macuni!news
From: news@macuni.mqcc.mq.oz (USENET News System)
Newsgroups: comp.sys.mac.comm
Subject: Re: Very High Speed Modems and Macs
Summary: Some Macs can do 57,600bps
Keywords: high speed serial port
Message-ID: <770@macuni.mqcc.mq.oz>
Date: 14 Nov 90 22:09:22 GMT
References: <85816@lll-winken.LLNL.GOV>
Reply-To: s8925188@mqcomp.mq.oz (Philip Craig)
Followup-To: comp.sys.mac.comm
Organization: Macquarie University
Lines: 41

>I'm interested in high speed modems, and I've been reading about new standards
>proposals for very high speed operation over standard phone lines. The only
>trouble with all this is finding serial port devices that will go that fast
>and writing system software to support them.Tthis naturally leads me to wonder
>just how fast the serial ports in Macs will go. I've seen measurements
>indicating that Macs have trouble keeping up with 19,200 bps data rates, but
>I believe this is due to software, not hardware. I know that my Mac IIcs can't
>keep up with my Telebit T2500 in either of its two fastest modes (PEP and
>V.42bis) with color turned on, and that it does much better with color turned
>off. Anybody out there in netland know how fast Apples modem port can operate,
From: s8925188@mqcomp.mqcc.mq.OZ (Philip Craig)
Path: mqcomp!s8925188

I have run *both* serial ports on a plain Mac II at 19,200 error-free, both
ports on an SE/30 and Mac IIx at 38,400bps error-free, and both ports on a
Mac IIfx at 57,600 error-free. The trouble is finding good software to keep
up at these speeds (I wrote my own).

I guess that a Mac servicing only one port (my application always used both at
once) would be able to keep up at higher speeds than this. Note also that
LocalTalk runs the port happily at approx 238,400bps and manages....even on the
old 128K Macs.

>and how fast the system software can send and receive data? Are there any
>plans to make them faster? Will the nuBus serial cards that can be used with
>the Comm Tool Box support any higher speeds? I'm thinking of the proposed
>ultimate modem standards, which have numbers like 56,000 bps, 78,000 bps, and
>even 100,000+ bps being bandied about in them. if these things come about, it
>sure would be nice to be able to use them. And for that matter, what of the
>possibility of an ISDN card that can offer all of the initial phase speed of
>144,000 bpc (to say nothing of the ultimate planned T1 speeds of 1.544 Mbps)?

Well the ISDN card won't be going through the built-in serial ports, so that
is not an issue. It will be limited by processor speed and the bandwidth of
either SCSI or NuBus or the PDS, none of which should be a problem.
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I've got this terrible pain in all the diodes down my left side...

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