Intel 537EX 1.1.2Windows 95 and Windows, User applications, Kernel - ring0, PCI bus, Hardware

Introduction

Figure 1. WDM Driver Block Diagram

User

applications

User applications

Kernel - ring0

Modem drivers stack

virtual COM

port,

channel

protocols

layer

WDM driver

Intels51.sys

PCI bus

Hardware

1.1.2Windows 95 and Windows 98

When the controllerless modem chipsets are used with Microsoft Windows 95 and Windows 98 applications, the traditional UART and serial port emulations are replaced by the proprietary HaM Mini Port driver (see Figure 2). Instead of transferring commands to UART virtual registers, then to a serial port, the HaM Port Driver sends commands directly to the Windows virtual machine driver VCOMM.VxD. This low-level communication driver supports the Win16 and Win32 Communication APIs. Like the WDM drivers, the Mini Port VxD drivers are fully plug and play and conform to Microsoft WHQL certification requirements.

8 536EX Chipset Developer’s Manual

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