Chapter 5 Input/Output Interfaces; Introduction; Enhanced Ide Interface; Ide Programming - Compaq Deskpro EP 6233 Technical Reference Manual

Chapter 5
INPUT/OUTPUT INTERFACES
5.

Chapter 5 INPUT/OUTPUT INTERFACES

5.1

INTRODUCTION

This chapter describes the system's interfaces that provide input and output (I/O) porting of data
and specifically discusses interfaces that are controlled through I/O-mapped registers. The I/O
interfaces are functions integrated into the south bridge and 87309 components. The following
I/O interfaces are covered in this chapter:
Enhanced IDE (EIDE) interface (5.2)
Diskette drive interface (5.3)
Serial interface (5.4)
Parallel interface (5.5)
Keyboard/pointing device interface (5.6)
Universal serial bus interface (5.7)
5.2

ENHANCED IDE INTERFACE

The enhanced IDE (EIDE) interface consists of primary and secondary controllers (integrated
into the south bridge component) that can support two IDE devices each. Devices that typically
connect to the IDE interface include hard drives, CD-ROM drives, power (writeable CD-ROM)
drives, and 120-MB floptical drives.
Two 40-pin keyed IDE data connectors (one for each controller) are provided on the system
board. Each board connector can support two devices and can be configured independently for
PIO or bus master (DMA) operation. DMA operation including Ultra ATA (UATA) modes up to
mode 2 (33 MB/s) are supported by both IDE controllers.
NOTE: With only device connected to a controller a 40-conductor cable 10 inches or
shorter will allow UATA mode 2 (33 MB/s) operation. Two devices on the same 40-
pin/10" cable will limit operation to UATA mode 1 (25 MB/s). For a controller to
provide UATA mode 2 operation with two devices connected an optional 80-conductor
is required. Pin 34 on the IDE interface is used by BIOS for 40-/80-conductor cable
detection. On the 40-conductor cable pin 34 is high (+5 VDC). On the 80-conductor
cable pin 34 is low (grounded).
5.2.1

IDE PROGRAMMING

The IDE interface is configured as a PCI device and controlled through standard I/O mapped
registers.
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page 5-15
page 5-21
page 5-28
page 5-35
Compaq Deskpro EP Series of Personal Computers
First Edition - April 1998
Technical Reference Guide
5-1