TRS-80 Model 100 pinouts

From: Paul Grammens <pgrammen_at_sonic.net>
Date: Tue Sep 8 19:12:50 1998

>Ok... It appears that the pins are _not_ numbered conventionally (from
>fig 6-5, Main PCB component side in the TechRef).
>
>They seem to be :
> 2
> 4 o 5
> o o
>1 o o o 3
>7 o 6 o 8
>
>The pinout is (from Fig 6-3, main PCB schematic
>
>1 TL (Telephone)
>2 Gnd (System logic ground)
>3 RxMD (Telephone line, Telephone common)
>4 RxM (Acoustic coupler receive)
>5 TxM (Acoustic coupler transmit)
>6 Vdd (+5V output to power acoustic coupler)
>7 TxMd (Telephone line)
>8 RP (5V CMOS logic input. Beleived to be for an external ringing
>detector unit for autoanswer. I can find no mention of this in the manuals)
>
>There are 2 switches on the left. One is marked Orig/Ans and selectes
>Originate or Answer tones. The other is marked ACOP/DIR and selects
>Acoustic coupler or Direct Connect operation.
>
>To link the thing up to a US phone line, direct connect :
>
>Connect the phone line to pin 3 and pin 7 on the connector. The official
>Tandy cable linked between a 'phone and the wall socket. The 'phone wires
>go to pin 3 and pin 1
>

I verified your pinout info by tracing the connections and connected the
red phone wire to pin 7 and the green wire to pin 3. When I ran the
terminal program it hung and the internal speaker made a continuous static
hiss. I exited the terminal program with a break command, and the static
stopped.
One thing I'm confused about is your direction to connect the phone line to
pin 3 and 7, but saying that the Tandy cable goes to pins 3 and 1. I must
be missing something here. I looked up phone wiring, and found that the
green wire is called "Tip" and is like a common, and the red wire is "Ring".

Any ideas on where I went wrong?
-Paul
Received on Tue Sep 08 1998 - 19:12:50 BST