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Connecting to internet thru a telnet server (by serial/eth conv)


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Hello everyone,

I got one of those cheap and small Ethernet/serial converters developed by USR. The one I got is the USR-tcp232-t2.

The device is super cool, since it is so small and it already work at TTL (not really, it work at 3.3v) so you don't need max232 or similar ICs.

It is not as sophisticated and full of options as UDS devices, but it is useful.

So I added a 74ls00 to connect/disconnect the data lines following the legacy rverter/sx212 circuit. Rverter handler uses the Motor line to control this. Before I connected directly, but the problem was the disk drive became unusable because the data lines were taken by the serial connection. Now with the 74ls00 connected to SIO motor line I can do disk directory, or xmodem, ymodem or xmodem transfers to/from disk drive.

The usr-tcp232-t2 is directly powered by SIO 5v. TX output 3.3v is enough to activate the 74ls00 so Atari SIO data in receive the 5v. The sio data out voltage was reduced to 3.3v just by using a voltage divisor and it worked without problems (I'm connected at 9600 baud)

The only problem that I am having now is how to emulate the telnet initiation protocol (the IAC codes), since the converter just connects using a true pure TCP connection.

A quick solution I found was to run socat tcp listening to a port, so the converter connect to it, and then connect that to a fake serial device like /dev/ttyMine and then run Getty in another console listening to the fake device ttyMine

It worked but is too convoluted.

I also tried to answer the right binary sequence to the IAC codes sent by the server but I could not get the linux login prompt.

I also tried socat tcp listen and connect directly to exec: bash

It worked but not always, and you don't get the login prompt, you go directly to the bash, obviously. it is still a little too complicated, because still I need to run it every time I want to connect.

So I'm running out of ideas of how make this run smoothly. With good terminal emulation to be able to run lynx or links, to access pigwa or Atariage, for example, with support of zmodem or xmodem.

I'm using bobterm and icet on a 65xe with additional memory, so transformed to a 130xe.

My idea is also to put everything in a project enclosure with a sio cable so it would be always connected (it could be inside the Atari, but I don't want to do perforations in the Atari case).

Please help me with your ideas.



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