I reviewed five Ultra SCSI host adapters for this article: Adaptec's AHA-2940U Ultra SCSI host adapter, AdvanSys' ABP-980U quad-channel (yes, that's four separate SCSI channels) narrow Ultra SCSI host adapter, Mylex/BusLogic's FlashPoint LT Ultra SCSI host adapter, QLogic's QLA-1040 Ultra SCSI host adapter, and Symbios Logic's SYM8751SP Ultra SCSI host adapter. For this review, all the adapters had to be Ultra SCSI compatible (i.e., up to 20MBps synchronous burst transfer rate, use of Bus Master­third-party­direct memory access, and a PCI bus interface).

Adaptec AHA-2940U
The Adaptec AIC-78XX chipset is an institution in the world of SCSI. Standalone SCSI host adapters from Adaptec (such as the Adaptec AHA-294X/394X family of adapters), SCSI host adapters from other manufacturers, and the embedded SCSI interfaces on many system motherboards use this chipset. As a result of its popularity among users and system vendors, this chipset and the adapters based on it enjoy a high level of compatibility with many SCSI devices and support from SCSI device manufacturers and software developers. For my review, I obtained an AHA-2940U narrow Ultra SCSI host adapter, which uses the AIC-78XX chipset.

In addition to its internal 50-pin narrow SCSI connector, the AHA-2940U contains one Micro DB-50 fifty-pin connector on the card's bracket to connect external SCSI devices. As with all the cards in this roundup, this adapter is jumperless and supports Plug and Play. The system automatically assigns adapter resources such as IRQ and upper memory addresses at startup. The adapter also supports other ancillary SCSI host adapter features such as bootable CD-ROM and SCSI Configured AutoMatically (SCAM) support. Microsoft has included support for Adaptec SCSI host adapters with every version of NT shipped, and Adaptec provides driver updates on its Web site.

AdvanSys ABP-980U
A relative newcomer to the SCSI market, AdvanSys is a company whose sole purpose is the manufacture of high-quality, high-performance SCSI adapters. AdvanSys uses a proprietary RISC processor on each SCSI host adapter to yield high levels of performance. Several different models are available (including wide Ultra SCSI and single channel versions). I received a quad-channel ABP-980U Ultra SCSI host adapter for review. This adapter has the unique feature of housing four independent Ultra SCSI channels on one adapter. Although my tests called for only one narrow Ultra SCSI channel, I was impressed by the fact that this card can fit four 50-pin narrow SCSI connectors on one full-length card.

The ABP-980U contains four internal 50-pin narrow SCSI connectors and one external high-density 50-pin connector. Although NT 4.0 does not ship with a default driver for this card, AdvanSys provides NT 4.0 drivers on its FTP site.

Mylex/BusLogic FlashPoint LT
As part of its acquisition of BusLogic, Mylex took over production of the BusLogic FlashPoint line of SCSI host adapters. These adapters include narrow, wide, dual channel, and dual channel wide adapters, and round out Mylex's high-end hardware RAID controller offerings.

The FlashPoint LT is a PCI Ultra SCSI host adapter based on BusLogic's proprietary SCSI chipset. It contains internal and external narrow Ultra SCSI interfaces, and it supports several features including SCAM, auto-termination, and a special SeqEngine SCSI command optimization feature for reducing CPU overhead. NT 4.0 ships with a driver for the FlashPoint family of adapters, and Mylex provides driver updates on its Web and FTP sites.

QLogic QLA-1040
QLogic manufacturers high-performance SCSI chipsets and complete adapter solutions. You can find QLogic chipsets on several RAID controllers and system boards, including many Digital Equipment Alpha platforms. QLogic was one of the first vendors to deliver a 64-bit PCI adapter, another reason for this company's popularity on the natively 64-bit Alpha platform.

I obtained a QLA-1040 32-bit PCI Ultra SCSI host adapter for my review. This Adapter contains both wide and narrow SCSI connectors and one channel. In addition to having standard Ultra SCSI compliance and bus mastering features, this adapter uses a dual-processor ISP1040B chip for minimizing CPU utilization and provides up to 10,000 I/O operations per second. It also uses one PCI bus interrupt per SCSI I/O operation and is field-upgradeable thanks to its use of a Flash ROM BIOS. NT 4.0 ships with a driver for the QLA-1040 adapter, and QLogic provides driver updates on its Web and FTP sites.

Symbios Logic SYM8751SP
Symbios Logic is another manufacturer of high-quality SCSI adapters. You can find chips based on the Symbios Logic family of SCSI chipsets on several motherboards, SCSI host adapters, and SCSI RAID controllers from various manufacturers. The SYM8751SP host adapter that I received for this review is a 32-bit PCI Ultra SCSI host adapter that supports both wide and narrow Ultra SCSI devices. This card has separate 68-pin and 50-pin interfaces and an external wide Ultra SCSI interface. The adapter is based on the Symbios Logic SYM53C875 chipset, and it supports transfer rates of up to 40MBps (wide Ultra SCSI). Symbios Logic provides driver updates on its Web site.