Apple Express Fax/Modem - Manual (Page 116)

Communications Toolbox compatibility
The Express Modem is designed to work with the Communications ToolBox
(CTB). The Express Modem Tool, a CTB connection tool, is designed to work
specifically with the Express Modem. If you use an application which uses
the CTB, it is preferable to choose the Express Modem Tool, rather than
selecting the Serial Tool, the Apple Modem Tool, or disabling the CTB.
The Express Modem provides access for those serial driver applications which
do not support the CTB. Selecting Use Express Modem in the Express
Modem control panel will enable applications using Serial Port A (Modem
Port) to communicate with the Express Modem.
Applications that use a non-standard means of accessing a modem (for
example, bypassing the serial driver and directly controlling the hardware, or
implementing an alternate to the standard serial driver) have no means of
accessing and using the Express Modem.
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