Windows 95 supports the Network Device Interface Specification (NDIS) versions 2.x and 3.1 protocol and adapter drivers, and provides an NDIS 3.1 replacement for version 3.0 drivers, which are incompatible with Windows 95.
By using NDIS 3.1 drivers, Windows 95 can support a wide range of network media, including Ethernet, token ring, and ArcNet®. The NDIS 3.1 specification accommodates Plug and Play features, so that in many cases network adapters can be added and removed dynamically while the computer is running. The related features and benefits are summarized in the following discussion.
Plug and Play support for network protocols and adapters.
Because of Plug and Play enhancements, the operating system can determine automatically the adapters to which each protocol should bind. If a Plug and Play event occurs, such as removing a PCMCIA network adapter from a portable computer, the NDIS 3.1 protocols and network adapter drivers remove themselves from memory automatically. (This Plug and Play capability is supported for most PCMCIA adapters, but not for most ISA adapters, which have power considerations.)
New NDIS mini-driver model.
The mini-driver provided by the adapter manufacturer implements only the half of the Media Access Control (MAC) layer functionality that is specific to the network adapter, which includes establishing communications with the adapter, turning on and off electrical isolation for Plug and Play, providing media detection, and enabling any value-added features the network adapter may contain.
The Windows 95 NDIS wrapper implements the half of the MAC functionality that is common to all NDIS drivers. The new mini-drivers are faster and roughly 40 percent smaller than earlier versions of NDIS 3.x network adapter drivers. The Windows 95 mini-drivers are also binary-compatible with Windows NT 3.5 mini-drivers, which means they can be used without recompiling. (You can recognize a mini-driver by its .SYS filename extension; other drivers have .VXD extensions.)
Real-mode NDIS 2 support.
An NDIS 2.x protocol under Windows 95 must use an NDIS 2.x network adapter driver. Both the protocol and network adapter drivers must load and bind in real mode before running for Windows 95. Values in PROTOCOL.INI are used to load the real-mode NDIS drivers, as described in Chapter 8, "Windows 95 on Microsoft Networks." However, you still use the Network option in Control Panel to configure NDIS 2 adapters.
When you run a real-mode network (for example, when using Safe Mode with Networking for system startup), Windows 95 uses NDIS 2 versions of NetBEUI and IPX/SPX protocols. These protocols are not intended for everyday use, since Windows 95 supplies faster protected-mode versions of these protocols. These real-mode protocols are also provided for client computers that start from a floppy disk and run a shared copy of Windows 95 from a server.
Windows 95 also supports existing ODI drivers with Novell® NetWare®-compatible network clients. For information, see Chapter 9, "Windows 95 on NetWare Networks."