Re: LZ: Cassette system
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Re: LZ: Cassette system
On Wed, 11 Sep 1996, [ISO-8859-1] Jarkko V=E4=E4r=E4niemi wrote:
> Scott Rein:
> > Hold on a second. I thought that you would just store it as a backup.
> > How can the tape player respond to the tones the calculator makes? I
> > am sure that the calculator must send some confirmation tones for each
> > packet sent.
>=20
> This would need of course a receiving program made with ZShell.
> Programs would be on tape with some checksums, so it would be more=20
> reliable and wouldn't crash the calc.
There are a few reasons why I believe this Cassette system will not work
without significant outboard electronics:
1. The TI does not communicate with tones! It uses 2 signal lines at
either 0 or 5 volts.
2. 1 signal line is used to acknowledge incoming data or flag a
transmission error by the recieving calc. The other line is used
for the actual data transmission. Note that the recieving calc
regulates the transmission, based on how fast it is running (in
turn related to battery power)
3. The link port operates at variable speeds. The calculators use the
second signal line to regulate the transmission.
4. Even if you write a zshell program that will recieve using only 1 line
(+ ground) and disregard the second line, you will have no way to
clock the transmission. Because the TI has no internal timer,=20
and because most people won't have crystal-synced tape decks, you
won't be able to use sync-dependent protocol, meaning an clock
is necessary, meaning messy external electronics.
Personally, I think Mel Tsai's latest work looks a lot more promising.
-Isaac
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Isaac Salpeter
the ticalc.org project
isaac@ticalc.org
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