Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site qumix.UUCP Path: utzoo!watmath!clyde!burl!ulysses!cbosgd!ucbvax!decvax!ittvax!qumix!len From: len@qumix.UUCP (Leonard Labar) Newsgroups: net.micro,net.micro.apple,fa.info-mac Subject: Commodore to Mac null modem connection. Message-ID: <171@qumix.UUCP> Date: Sun, 25-Nov-84 20:03:38 EST Article-I.D.: qumix.171 Posted: Sun Nov 25 20:03:38 1984 Date-Received: Tue, 27-Nov-84 03:43:11 EST Distribution: net Organization: Qume Corp., San Jose, CA Lines: 49 Subject: Commodore to Mac Null modem cable The first chart below works for connecting a Mac to a Vicmodem. The second chart is a null modem cable for connecting a Mac to a Vic20 or C64. I just got it working. What this does is (1) saves me $471 since I already have a dot matrix printer connected to my Vic (2) saves me $1600 since I can use the Vic to debug Mac SW without buying a 2nd Mac. -----RS422 (+5 volts line driver/receiver)------ MAC function breadboard VICMODEM function (conn. 1) 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 / -------- Null modem cable: conn. 1 signal conn. 2 (to CBM) 1,A GND 1,A M TXD --> B,C (RXD) C <-- RXD M (TXD) H to GND carrier detect H to GND So now I can type on the CBM keyboard and everything appears on the Mac