[net.micro.cbm] What do I buy to get RS-232 on a C64?

msm@rabbit.UUCP (10/18/83)

I have to order a Commodore 64, a monitor (1701?), disk drive, and
something to give it real RS-232.  Can anyone supply part numbers,
and advice if there are any strange things that happen using the
RS-232?  [I'm an Atari owner, so I expect strange things to happen]
Please reply by mail.  Thanks.