RS-232C Interface for C64/C128 ------------------------------ Below diagram shows one of the simplest method to build an adaptor to hook an external modem to a C64. I guess you can find the IC 7404 easily. With a C128 it can go up to 9600 bps, but for a stock C64 it requires very special tricks to access the limiting speed of 2400 bps. The schematics belongs to Walter Wickersham ( shadow@connected.com ). user port RS232 DB25 DB9 description --------- ---------- --- ----------- A & N------------------------+-----------1 & 7 5 ground _____ I B & C----------------[2 7]-+ [ ] M------------------[3 1]-------------3 2 rx [ ] 2------------------[14 4]-------------2 3 tx [_____] Part List --------- 7404 IC (you can easily find it) DB25 male connector (or DB9 male) User Port connector 2m. 2 line shielded cable. (you don't need this if your modem has the cable) Connector Views (looking at the front faces) --------------------------------------------- user port DB25 DB9 1 1 1 1 1 1 1 1 2 3 4 5 6 7 8 9 0 1 2 3 1 2 3 4 5 1 2 3 4 5 6 7 8 9 0 1 2 \-----------------------------/ \-------------/ - - - - - - - - - - - - \ . . . . . . . . . . . . . / \ . . . . . / - - - - - - - - - - - - \ . . . . . . . . . . . . / \ . . . . / A B C D E F H J K L M N ------------------------- --------- 1 1 1 1 1 1 2 2 2 2 2 2 6 7 8 9 4 5 6 7 8 9 0 1 2 3 4 5 Ilker Ficicilar filker@newton.physics.metu.edu.tr e068214@narwhal.cc.metu.edu.tr ---