III.INSTALLATION

21.Fast (50 pins)/Wide (68 pins)/Ultra2 (68 pins) SCSI Connectors

This motherboard has onboard 50-Pin Fast SCSI connector for 8-bit SCSI de- vices, 68-Pin Wide SCSI connector for 16-bit SCSI devices, and 68-Pin Ultra2 SCSI connector for 16-bit differential SCSI devices.

50-pin Fast

SCSI II Connector 68-pin Wide

SCSI Connector

68-pin Ultra2

SCSI Connector

P2B-D/P2B-DS Onboard SCSI Connectors

IMPORTANT: The 68-pin Wide SCSI Connector is always terminated and will only work as an end device.

NOTE: Up to 15 devices can be connected with 50-Pin Fast-SCSI and 68-Pin Ultra- Wide SCSI combined.

The onboard Adaptec AIC-7890AB chipset (optional) incorporates an advanced multimode I/O cell that supports both single-ended (SE) and Ultra2 devices. With Ultra2 devices, the SCSI bus platform performs at full Ultra2 speeds (up to 40 MB/sec in 8-bit mode and up to 80 MB/sec in 16-bit mode) and extended cabling 12m (or 25m in a point-to-point configuration). When an SE device is attached, the bus defaults to an SE speed and cable length.

In mixed environments of Ultra2 and SE devices, the onboard host adapter can be coupled with the Adaptec AIC-3860 transceiver chipset (optional) to bridge the compatibility gap. By dividing the SCSI bus into independent SE and low voltage differential (LVD) segments, the transceiver chipset supports legacy devices without limiting performance and cable length on the LVD segment.

INSTALLATION

Connectors

III.

 

 

 

PCI Bus

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PCI-to-Ultra2

(LVD)

 

 

 

 

Adaptec AIC-7890AB Chipset

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

L LVD Mode

S Adaptec AIC-3860 Chipset

Ultra2 SCSI

SE Mode

Wide SCSI Connector

Connector

Single-Ended Devices

CD-ROM Scanner Tape

Ultra2 Devices

Disk 1 Disk 2 Disk 3

P2B-D/DS Mixed Ultra2 and Single-Ended Device Configuration

Ultra2 SCSI uses the same connectors and cables as UltraSCSI, so upgrading is easy and cost-effective.

ASUS P2B-D/P2B-DS User’s Manual

33