TRS-80 Model 100: Phone port pinout

From: Tom Owad <>
Date: Sat Feb 5 12:53:21 2005

Using these pinouts:

Model 100 Phone port:
> 8 U 7
> 3 6 1
> 5 2 4
> 1 TL Conventional Telephone Unit
> 2 GND Logic Ground
> 3 RxMD Direct connection to TEL line (RING)
> 4 RxMC Accoustic coupler connection (MIC)
> 5 TxMC Accpustic coupler connection (Speaker)
> 6 VDD - No description bit it should be easy to figure out -
> 7 TxMD Direct connection to TEL line (TIP)
> 8 RP Ringing Paluse (as spelled in manual)

2.5mm Audio jack:
> Tip - Mic
> Ring - Headphone
> Sleeve - Ground (Common)

I connected pin 4 to the jack's tip, pin 5 to the ring, and pin 2 to the

DIR/ACP is set to ACP and ANS/ORIG is set to ORIG. Stat is set to
M8N1e,10 pps. I dialed the Club 100 BBS (925-939-1246) and confirmed
that a modem answered. With the Model 100 connected, I called again,
dialing via the phone. The system doesn't give any indication that it
connects and I'm not sure how I can listen in, without wiring up a
speaker, too. When I switch to TERM mode, the system gives a very faint
beep and then apparently freezes and I need to reset it. Sometimes I
need to reset multiple times to make the keyboard work again. The keys I
enter in TERM mode are then typed into the "Select" field of the Menu.

Upon further experimentation, TERM freezes the system whether I'm
attempting to connect to the BBS or not. I have two more Model 100's I
can dig out and experiment with, but I don't _think_ TERM behaved this
way before I started experimenting with this setup.

As the cell phone is dialing, should the Model 100 be in TERM mode?
Should it be possible to use F8 to exit, or any other key combinations?


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Received on Sat Feb 05 2005 - 12:53:21 GMT

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