The new Windows 95 communications subsystem allows applications to transmit data quickly and reliably and to cooperatively share communications devices. The new kernel and communications architecture in Windows 95 provide the following benefits:
Improvements over Windows 3.1.
Windows 95 replaces the monolithic communications driver architecture of Windows 3.1 with a modular driver model that allows other software and communications device manufacturers to easily plug in new communications device drivers.
High-speed reliability.
Windows 95 supports reliable, high-speed communications. It avoids loss of characters by keeping up with data coming in from the communications port. To quicken communications, the amount of code in the kernel that can be used by only one process at a time (critical sections) has been reduced. In addition, the network architecture and the 32-bit, protected-mode file system of the communications subsystem reduce required mode transitions and interrupt latency. The data-transmission speed in Windows 95 is limited only by the hardware characteristics of the computer, such as the processor speed and type of communications port. Windows 95 supports communications devices with higher transmission speeds than base RS-232 devices. For example, it supports Integrated Services Digital Network (ISDN), which can communicate at speeds of 64 or 128 kilobits per second, if an ISDN vendor provides a driver.
Higher data throughput.
The 32-bit communications subsystem takes advantage of the preemptive multitasking architecture of Windows 95 to provide better responsiveness to communications applications, thus supporting higher data throughput. Consequently, communications transfers in Win32 applications are not as affected by other tasks running in the system as were Win16-based applications under Windows 3.1.
Support for Plug and Play and legacy communications devices.
Plug and Play support and device installation wizards simplify installation and configuration of Plug and Play and legacy modems and communications devices.
Device sharing among communications applications.
The telephony application programming interface (TAPI) arbitrates among applications that want to share the same communications ports and devices. For example, while Dial-Up Networking waits for an incoming call, Microsoft Fax can send an outgoing fax without the user having to close Dial-Up Networking.