Specifications

Intel
®
810E2 Chipset Platform
R
Design Guide 59
Figure 28. Combination Host-Side / Device-Side IDE Cable Detection
80-conductor
IDE cable
IDE drive
5 V
ICH2
GPIO
GPIO
Open
IDE drive
5 V
40-conductor
cable
IDE drive
5 V
PDIAG#
ICH2
GPIO
GPIO
IDE drive
5 V
Resistor required for
non-5V-tolerant GPI.
PDIAG#
PDIAG#PDIAG#
Resistor required for
non-5V-tolerant GPI.
10 k
Ω
10 k Ω
To secondary
IDE connector
To secondary
IDE connector
PDIAG#/
CBLID#
PDIAG#/
CBLID#
10 k Ω
10 k Ω
10 k Ω
10 k Ω
IDE_combo_cable_det
This mechanism allows the BIOS, after diagnostics, to sample PDIAG#/CBLID#. If the signal is High,
then there is a 40-conductor cable in the system and ATA modes 3, 4 and 5 must not be enabled.
If PDIAG#/CBLID# is detected Low, then there may be an 80-conductor cable in the system or there
may be a 40-conductor cable and a legacy slave device (Device 1) that does not release the
PDIAG#/CBLID# signal as required by the ATA/ATAPI-4 standard. In this case, the BIOS should check
the Identify Device information in a connected device that supports Ultra DMA modes higher than 2. If
ID Word 93, bit 13, is set to 1, then an 80-conductor cable is present. If this bit is set to 0, then a legacy
slave (Device 1) is preventing proper cable detection, so the BIOS should configure the system as though
a 40-conductor cable were present and then notify the user of the problem.