Re: LZ: Zterm & Modems
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Re: LZ: Zterm & Modems
On Sun, 06 Oct 1996 11:32:45 -0500, you wrote:
>Jarkko V=E4=E4r=E4niemi wrote:
>>=20
>> I've found simple modem chip from National Semiconductor, that could
>> perhaps be hooked straight to link port. I have ordered free sample
>> and will have a look at it if it could be used. Though it's only
>> 300bps, but that'll be just fine for irc/mud/telnet etc..
>> One problem with this could be timing, but perhaps the timer used
>> with busy indicator could be used with this, or there is some other
>> some solution. ;-)
>> This chip is "MM74HC943", put that into search field in
>> www.national.com and you should find it.
>> -------
I saw that chip a few months ago, and it looks pretty good. However,
the reason I didn't look further is because the vast majority of BBS's
and dial up access accounts won't even let you connect at 1200 any
more, much less 300. Therefore it would only be useful as a novelty
item or a simple data transferr method to a remote computer. Note
that the datasheet doesn't give you specs on the RJ-11 connection, and
I doubt you'd want a handset coupled connection. You might have to do
some fishing to find out how to connect this thing properly.
>even though i am not doubting your way, the graphlink-ADAPTER-external
>modem way of connection has already been proven to work. Also the g-A-em
>way goes at 9600 baud which is the fastest baud rate that the graphlink
>can handle.
>PCoMP
>Visit Maximus Productions home page at: http://www.ntsource.com/~pcomp
>
Actually, it is theoretically possible to transferr at much higher
rates than 9600. With an efficient algorythm you can probably get up
to 14.4 speed. If you figure 10 bits per byte, and 1.4k bytes per
second, that leaves a cycle time of about 70 uS. At "raw" speeds the
TI-85 can probably get up to about 1 uS per cycle, and with real
software control I estimate cycle times of 25-50 us, meaning that we
can probably go even faster than 14.4, maybe 28.8 on turboed calcs.
This is all speculation, though, as the program would be so complex
that real send/receive tasks may not be able to keep up, but in
"burst" mode it should work.
-Mel
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