Re: TI-H: Data Transfer Idea
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Talking about ISDN, would there be anyone here who would know what to do
with the National Semiconductor ISDN chip? It seems interesting and, even
if the link port isn't that fast, it would be nice to use it as an ISDN
modem for ISDN lines (and maybe even make it compatible with computers so
that you can hook up a cheap ISDN device to the comp through like the
parallel port or something...?).
"This is the most logical route, Captain"
-= Zenon@bbs.nexes.com =-
----------
: From: ti-hardware@lists.ticalc.org
: To: Zenon
: Subject: Re: TI-H: Data Transfer Idea
: Date: November 5, 1996 1:01 PM
:
:
: C.J. Oster wrote:
: >
: > Ok, all this time, we've been trying to use both lines for data
: > transfer. If we use both, then we are esentially using sterio sound,
but
: > modems work great on mono. Sure if you are hard wired to gether, then
the
: > connection goes red-red, and white-white. But in a radio transmitter,
we
: > can transmit on one, and recieve on the other. Or we could just use
one
: > line and employ a protocol that modems use to transfer. This is where
you
: > guys come in... The most efficient transfer protocol is by far Xmodem
CRC,
: > right (assume that were leaving out isnd and T3 lines). Does somebody
know
: > EXACTLY how it takes care of errors? Don't reply saying that it has
: > something to do with a checksum bit, I know that. Then you could leave
you
: > calc on waiting for a signal, and when you get a request, you could
play a
: > game, or chat, or whatever.
: >
:
: Uhh.. no.. Xmodem is ancient. There a million (well, not really) better,
: newer, faster protocols. Ymodem and Zmodem, for example.. ISDN and T1/T3
: are entirely different.. They're digital. No Xmodem, Ymodem, Zmodem, or
: anything like that is even involved.. They've got their own entirely
: different system.
:
: Checksums add up all the bits (or bytes) in a packet, run it through a
: math formula of some sort (different formula for each type of checksum)
: and you come out with an answer. That's the checksum. No, I don't happen
: to know any checksum formulae off hand...
:
: --
: Greg Hill
: http://braves.bhs.davis.k12.ut.us/
: ghill@lab.tech.bhs.davis.k12.ut.us
: greg_hill@email.state.ut.us
References: