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RS232 over the joystick port


jrhodes

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I remember hearing that the TI's joystick port can be used as a rs232 port.

The person writing the article even transmitted a small amount of data over it, if i recall correct.

Unfortunately i can not seem to find that article right now.

Any one know the article in question and where to find it?

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Totally forgotten about this project. Has anyone ever built it?

 

I did not build it but I came by one some years ago. Once I identified what it was I found someone that was interested in having it so I sent it to them. He said it worked. But it will not work with the standard terminal programs out there since it uses the joystick port.

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It looks like the TMS9919 can get to 19,200 BPS and maybe even 38.4Kbps.

 

At that speed the CPU could barely keep up with the data while receiving a continuos stream, I should think.

 

I you added the overhead of reading bits on the 9901 with the 9900 CPU, how does it manage to do it faster?

 

I am amazed.

 

Side question, what is the effective BPS rate of the Cassette save/load system?

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It looks like the TMS9919 can get to 19,200 BPS and maybe even 38.4Kbps.

 

At that speed the CPU could barely keep up with the data while receiving a continuos stream, I should think.

 

I you added the overhead of reading bits on the 9901 with the 9900 CPU, how does it manage to do it faster?

 

I am amazed.

 

Side question, what is the effective BPS rate of the Cassette save/load system?

Hmm you put RAM on the 16 bit bus, so this smokes the RS232 performance.

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What baud rate can you get out it Tursi?

It ran through subroutine calls in MiniMemory, and basically toggled the joystick select lines. It was output-only, no hardware for data input (except it supported one or two of the printer status signals). I only ran it at 1200bps, I don't remember what it could get to (but the article is linked above ;) ).

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