Chapter 5 Input/Output Interfaces; Introduction; Enhanced Ide Interface; Ide Programming - Compaq W4000 Technical Reference Manual

Chapter 5
INPUT/OUTPUT INTERFACES

5. Chapter 5 INPUT/OUTPUT INTERFACES

5.1

INTRODUCTION

This chapter describes the standard (i.e., system board) interfaces that provide input and output
(I/O) porting of data and specifically discusses interfaces that are controlled through I/O-mapped
registers. The following I/O interfaces are covered in this chapter:

♦ Enhanced IDE interface (5.2)

♦ Diskette drive interface (5.3)
♦ Serial interfaces (5.4)
♦ Parallel interface (5.5)
♦ Keyboard/pointing device interface (5.6)
♦ Universal serial bus interface (5.7)
♦ Audio subsystem (5.8)
♦ Network interface controller (5.9)
5.2 ENHANCED IDE INTERFACE
The enhanced IDE (EIDE) interface consists of primary and secondary controllers integrated into
the 82801 ICH2 component of the chipset. Two 40-pin IDE connectors (one for each controller)
are included on the system board. Each controller can be configured independently for the
following modes of operation:
♦
Programmed I/O (PIO) mode – CPU controls drive transactions through standard I/O mapped
registers of the IDE drive.
♦
8237 DMA mode – CPU offloads drive transactions using DMA protocol with transfer rates
up to 16 MB/s.
♦
Ultra ATA/100 mode – Preferred bus mastering source-synchronous protocol providing
transfer rates of 100 MB/s.
NOTE: These systems include 80-conductor data cables required for UATA/66 and /100
modes.

5.2.1 IDE PROGRAMMING

The IDE interface is configured as a PCI device during POST and controlled through I/O-mapped
registers at runtime.
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Compaq Evo and Workstation Personal Computers
Featuring the Intel Pentium 4 Processor
Second Edition - January 2003
Technical Reference Guide
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