Re: TI-H: Talk 85
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Re: TI-H: Talk 85
On Sat, 9 Nov 1996, Tony Lieuallen wrote:
> The file you attached is about doing it yourself via ASM. When I
> referred to there being a clock signal, I meant in the way that TI does
> it the way it's built into the calc, and I am 99% sure that that is correct.
Let me be the first to assure you that you are wrong. The TI does not use
a clock line in its link protocol.
One line is DATA, the other line is ACK (for ACKnowledge). Which line is
which depends on the state (1 or 0) of the bit being sent.
Essentially, to send a bit of information, the calculators do as follows:
Sending calc pulls one line to ground (which line is pulled depends on
which logical bit is sent. I believe pulling red signifies 0 (and white =
1). The recieving calculator ACKnowleges the bit by pulling the other
line (i.e. whichever line is still at 5v) to ground. When the sending calc
sees that both lines are at 0v, it resets both lines to +5v.
The process is repeated for each bit sent.
-Isaac
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Isaac Salpeter
the ticalc.org project
isaac@ticalc.org
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