This User Guide provides software installation information for the Adaptec AHA-1740A, 1742A, and the 1744 EISA-to-fast-SCSI bus master host adapters. Cumulatively the cards are referred to as AHA-1740A/1742A/1744 in this guide. The Adaptec adl.exe download utility and the ASW-C174and ASW-M174software packages are described, as well as available software support.
General Product Information
The AHA-1740A/1742A/1744 provides a high performance connec- tion between the EISA (Extended Industry Standard Architec- ture) bus and the SCSI (Small Computer System Interface) bus. The AHA-1740A/1742A are single-endedSCSI host adapters that support single-ended disk drives. Single-ended host adapters and devices can support cable lengths of up to 6 meters (about 18 feet). Most of the SCSI drives on the market today are of this type. The AHA-1744 Host Adapter is a differential SCSI host adapter that supports differential type SCSI devices. The use of differential SCSI drives and adapters allows the SCSI cable length to be up to 25 meters in length (about 75 feet). Other than this basic difference, and other slight differences discussed in this document, the AHA-1740A/1742A/1744 are installed and operate identically.
The AHA-1740A/1742A/1744 is a bus master device and transfers data into host memory at burst rates of 33 MBytes/sec. These transfers are generally 32 bits wide, unless transferring data into 8- or 16-bit memory. This form of transfer is known as bus mas- ter DMA (Direct Memory Access). Bus mastering minimizes host CPU overhead, since the AHA-1740A/1742A/1744 has an on board processor to transfer data directly to memory. This is the highest performance type of data transfer available for the EISA bus in multitasking operating systems.
