There are many ways that synchronous communications can be performed on a
Macintosh. The type of hardware and software needed is usually linked to
the type of host computer that you want to connect to. Also, the hardware
performs the synchronous interface, rather than the terminal emulator
itself. The software must be able to communicate with the specific
hardware: most of the time, each particular type of synchronous
communications hardware has software written specifically for it.
For instance, MacTerminal can be used for synchronous communications with
an IBM host through the use of an AppleLine protocol converter, but other
standard Macintosh terminal emulators can NOT be used in the same fashion.
It is the AppleLine that actually performs the synchronous communications,
while MacTerminal is communicating asynchronously with the AppleLine.