len@qumix.UUCP (Leonard Labar) (10/26/84)
Subject: vicmodem to rs422 conversion I just got this working!!! It only cost me $1.60 for the 9 pin connector since I already had the $59 vicmodem and scrap parts. Some will scoff but this is a poor man's modem for the Macintosh. A bit slow (300 bps) but when the wife watches the budget you have to start somewhere. I also have a home-brew auto dial circuit but I haven't converted that from the vic to mac yet. -----RS422 (+5 volts line driver/receiver)------ MAC function breadboard VICMODEM function 1 ground ground 1, A ground 2 +5v pwr to ic ----- 4 TXD+ --> 3.3k pullup --> M data to modem 5 TXD- ---- ---- 6 filtered +12v ---- 10 modem power 7 carrier detect<- LS04-6 5 to <- H carrier detect 8 RXD+ ---- ----- 9 RXD- <-- LS04-4 &1k res., 3 to <-- C data from modem back of mac ------------- \ 5 4 3 2 1 / \ 9 8 7 6 / -------- The MAC book (red cover) seems to say you can run the rs422 lines open ended like this. They talk about doing it with the imagewriter.