AIC-7890 Features

Increased SCSI Performance


With the AIC-7890 and AIC-7891 single-chip host adapters, performance takes a giant leap forward. Ultra2 technology doubles Ultra SCSI data transfer rates-up to 40 MByte/sec in 8-bit mode and up to 80 MByte/sec in 16-bit mode.

In addition, the AIC-7891 single-chip host adapter features a 64-bit PCI interface. This interfaces doubles the PCI bandwidth and will address the needs of next generation 64-bit workstations and servers.

These host adapters integrate several other performance-enhancing features. A 20-MIPS PhaseEngine® RISC processor off loads I/O command processing from the system CPU. And the data FIFO buffer is doubled to 512 bytes for more efficient PCI bus utilization.


Longer Cables


Using Low Voltage Differential (LVD) technology, these Ultra2 SCSI single-chip host adapters can support up to a maximum of 15 devices on a 12 meter cable. This represents a fourfold increase over UltraSCSI cable length. In a point-to-point configuration, cabling can be extended up to 25 meters. The increased cable length provides greater flexibility in system configuration, especially in clustering and RAID applications.


Backward Compatibility


The AIC-7890 and AIC-7891 incorporate an advanced multimode I/O cell that supports both single-ended and Ultra2 devices. With Ultra2 devices, the SCSI bus performs at full Ultra2 speeds and extended cabling. When a single-ended device is attached, the bus defaults to single-ended speed and cable length.

In mixed environments of Ultra2 and single-ended devices, the AIC-7890 and AIC-7891 host adapters can be coupled with an Adaptec AIC-3860 transceiver chip to bridge the compatibility gap. By dividing the SCSI bus into independent single-ended and LVD segments, the AIC-3860 supports legacy devices without limiting performance and cable length on the LVD segment. (see figure)

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




Optimizing performance in a mixed Ultra2 and single-ended peripheral configuration.


PCI interface

  • AIC-7890: 32 bit
  • AIC-7891: 64 bit

Up to 80 MByte/sec on the Ultra2 SCSI bus

  • Up to 40 MByte/sec data transfer rate in 8-bit mode
  • Up to 80 MByte/sec data transfer rate in 16-bit mode

20-MIPS PhaseEngine RISC processor for SCSI command processing

512-byte data FIFO buffer for efficient PCI bus utilization

Cache line streaming for improved PCI bus utilization

Dual Address Cycle (DAC) on the AIC-7890 chip and AIC-7891 provides greater system memory addressability

Target mode to support clustering, bridge and RAID applications

Tagged command queuing allows changes in the order of SCSI command execution to improve performance


Additional Features

Advanced multimode Ultra2 SCSI I/O cell for supporting single-ended or Ultra2 devices

JTAG boundary scan to support system level interconnect testing 3.3V / 5V PCI interface for providing flexibility for designing high-performance, low-power systems

Enhanced Logical Unit Number (LUN) supports up to a maximum of 32 LUNs

ARO-1130 series support and RAIDport II compatible

Microsoft® Windows NT® Wolfpack clustering compatible

I2O-ready system compatible

Software Support

Microsoft Windows NT, Windows® 95, Novell NetWare, SCO Openserver, SCO UnixWare, IBM OS/2, and Sun Solaris

SCSI Device Support

Connection for up to 15 SCSI devices

Support for a combination of 8-bit and 16-bit Ultra2, Ultra, and standard SCSI devices including disk drives, tape drives, CD-ROM and CD-Recordable drives, jukeboxes, removable drives, scanners, printers, and disk arrays.