Vic to Mac Null modem cable.

[Info-Mac]

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From: [email protected] (Leonard Labar)
Newsgroups: net.micro.cbm,fa.info-mac,net.micro,net.micro.apple
Subject: Vic to Mac Null modem cable.
Message-ID:
Date: Mon, 29-Oct-84 00:38:33 EST
Article-I.D.: qumix.148
Posted: Mon Oct 29 00:38:33 1984
Date-Received: Sat, 3-Nov-84 03:53:19 EST
Distribution: net
Organization: Qume Corp., San Jose, CA
Lines: 53


Subject: Commodore to Mac Null modem cable

I recently posted the interface below to the net. It works. Since
then I've added a second cable that after unplugging the modem allows
one to interface direct from the Commodore to the Mac. Its'
description is listed below the first.

-----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 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
screen that I type. Big deal! Only problem is it doesn't work the
other direction. I'm sure I don't have any faulty connections.

Q. Anybody know the answer to the above problem?
Q2. Is there a way for the Mac to receive and store M-Basic files via
the modem port? I have a lot of files without peeks and pokes that I
could use if I can do this.