Re: Tape85

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Re: Tape85

Jeff Tyrrill <Jeff_Tyrrill@MSN.COM> muttered:

->The commands must do some handshaking. They can be used to "steal"
variables
->from another TI-85, as long as the other calc is at the Home Screen.
It can't
->just read the memory through the link port; handshaking would have
to occur.
->________________

I am not quite sure in what fomrat you plan to store the information
on the tape. Am I right in assuming that you plan some sort of
Frequency Shift Keying, in that I mean you have one tone for 0 and
another for 1? Or do you have a greater variety of tones? Basically I
am wondering in what form these tones are sent. A definite
possiblility could be to use a single tone and then pick it up with an
NE567 tone decoder. This decoder sets a logic high whenever its input
contains a certain tone (this tone can be selected by the support
resistors, etc.) However, this decoder can be quite slow with low
tones. So, data rates couldn't probably exceed 300 bps. This speed
however would be acceptable and would allow the use of cheap tapes. Of
course, I haven't tried any of this out, and maybe greater data speeds
could be possible... BTW the NE567 costs about 0.47 US. Even with a
few resistors, and a jack we could be talking less than $5. I would
also suggest having a CRC on data on the tape. Possibly every block
should be written twice for realiability?

Perhaps something like a cable with a SPDT switch. This switch could
have a write setting which is simply a cable with no electronics, and
a read setting which switches the tone detector into the circuit?

Just some thoughts,
Neil Padgett
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