Apple Macintosh LC 630 DOS - Manual (Page 42)

Connecting an Apple PlainTalk Microphone
Your computer has a sound input port, which you can use to connect an Apple
PlainTalk Microphone.
Use PlainTalk only: You should connect only the Apple PlainTalk
Microphone. Other models of microphone will not work with your
Macintosh.
To connect the microphone, do this:
m Plug the microphone’s connector into the sound input port (marked with the icon X )
on the back of the computer.
Sound
input port Sound
output port
31 Connecting Additional Equipment