Mac/Atari Fusion: Connecting an Atari 8-bit to a Mac

Connecting an Atari 8-bit to a Mac

Until a better method is devised, the best way to connect your Atari to your Mac is with a serial cable (also known as a null modem cable) between the two. You will need the following:

An Atari 850 interface module (or other RS-232 enhancement)
9-pin DIN connector for Atari end
8-pin Mac Serial mini connector
A length of cable containing at least 4 wires, preferably shielded

This cable is not difficult to make. If you'd rather not do it yourself, a friend with a technical bent should be able to build one for you. (I had my dad, who is an engineer, help me with mine.) In a pinch, you can stick insulated wires with the ends trimmed into the holes in the ports--not the most elegant method, but supposedly it will work.

Once you have the two machines connected, you can use any modem or terminal software on each end. Be sure to specify "direct connect" in the connection preferences if it's available. Make sure the two computers are set to the same baud rate and are using the same transfer protocol. Rainbow comes with some simple transfer programs which also work well.

Proper Cable from Mac Modem Port to Atari 850 with full handshaking for use with terminal software. (Adapted from information from Apple's Tech Info Library)

The ports as viewed on the back of the Mac and the 850:
Mac 8 pin mini-modem          Atari 850 9 pin DIN connector
 or printer port)             (RS-232 port #1)

 · 8   · 7   · 6                · 5  · 4  · 3  · 2  · 1
 
· 5    · 4    · 3                  · 9  · 8  · 7  · 6

   · 2     · 1
Cable schematic:
Macintosh Mini-8 Port                     9 Pin RS-232 (850 Port #1)
Signal Name    Signal  Pin                Pin* Signal Signal Name
-------------  ------  ---                ---  -----  -------------
Handshake Out  HSKo    1  -------------->  6   DSR    Data Set Ready
Handshake In   HSKi    2  <--------------  1   DTR    Data Term Ready
Transmit -     TD-     3  -------------->  4   RD     Receive
Receive -      RD-     5  <--------------  3   TD     Transmit
Transmit +     TD+     6  Not connected
--             --      7  Not used
Signal Ground  SG      4  -----|---------  5   SG     Signal Ground
Receive +      RD+     8  -----|
The RD+ line must be grounded as shown or the reliability of the connection will be impaired, especially on Macs made since the SE. Cable may be up to 50 feet long.

It's possible to get by without the handshake lines, but depending on your terminal software, they may be required. Some transfer programs, such as those included with Rainbow, don't use them.