SCSI Card 2940U2W Q & A Revised 1/14/98 Hardware Q: What is the SCSI Card 2940U2W? A: The SCSI Card 2940U2W (or AHA-2940U2W) is the latest in the line of Adaptec PCI host adapters. It has the latest SCSI Ultra2 technology which uses Low Voltage Differential (LVD) circuitry designed into the CMOS to provide a bandwidth that is up to twice the current Ultra speeds and with cable lengths up to 25 meters. Q: What is Ultra2? A: Ultra2 is a subset of the SCSI-2 specifications. Using LVD technology, which has less susceptibility to noise and has reduced power consumption (due to the LVD designed into the chip technology), the adapter is able to support Ultra2 wide devices with a SCSI burst transfer speed of up to 80MB/sec and a point-to-point (one device) cable length of 25 meters, or 12 meters with two or more devices. Q: Can the SCSI Card 2940U2W support legacy devices? A: Yes. Due to the SpeedFlex(tm) transceiver chip, the AIC-3860, the SCSI Card 2940U2W provides two bus segments, an LVD Ultra2 wide segment and a Single-ended (SE) Ultra wide/narrow segment. The SCSI Card 2940U2W provides support for up to 15 total devices. Q: What is the maximum cable length for the SE Ultra segment? A: The cable length and transfer speed limitations of the Ultra bus segment is the same as the current Adaptec Ultra adapters (AHA-2940U, AHA-2940AU, and AHA-2940UW), which is 3 meters with four or fewer devices and speeds up to 40 MB/sec. Q: Is the LVD Ultra2 segment cable length limited by the length of the cable on the SE Ultra segment? Is it a combined cable length measurement? A: No. Each segment is electrically isolated and maintains the performance and configuration parameters of that segment, including termination requirements. Q: What is the connector configuration on the adapter? A: There are four connectors on the adapter. For the LVD Ultra2 segment, there are internal and external 68 pin connectors. For the SE Ultra segment, there is an internal 68 pin wide connector and an internal 50 pin connector. Q: Can all four connectors be used at the same time? A: Yes. Because the SpeedFlex(tm) transceiver controls the data flow on the card, each segment can be fully populated with up to 15 SCSI devices total as long as cable length parameters on each segment are observed. Q: Can I use legacy devices on the Ultra2 segment? A: Yes, you can use legacy devices on the LVD Ultra2 bus segment. Using an auto-sensing technology called Multimode I/O, the LVD Ultra2 segment can sense when a legacy Single Ended device is attached to the bus segment and switch to Ultra single-ended mode. Performance on the LVD Ultra2 bus then has the same parameters and limitations as the SE Ultra bus in regards to burst transfer speed and cable length. Q: Can I use the same cables for Ultra2 devices as I use for Ultra peripherals? A: It is recommended that you use cables specifically designed for Ultra2 devices. The SCSI Card 2940U2W kit contains a terminated Ultra2 Wide cable with connectors for four Ultra2 Wide peripherals. Q: Can I connect a Ultra2 device to the legacy SE Ultra Wide connector on the adapter? A: Yes, but severe performance penalties occur, as well as other factors, for the LVD Ultra2 device. SCSI Ultra2 devices do not have a termination option so cannot be installed as the only device on the cable or at the end of the cable. The adapter will not function if termination is not correct. When the LVD Ultra2 device is connected to the legacy bus segment, the Multimode I/O feature of the LVD/SE circuitry on the device drops it down to Ultra single-ended mode , with burst transfer speed and cable length limitations of the Ultra bus. Q: What are the computer requirements for the SCSI Card 2940U2W? A: The adapter requires a PCI 2.1 compatible PCI bus connection with Bus Mastering capabilities. Q: I don't have any LVD Ultra2 devices yet. Can I still install my SCSI-2 devices on both the legacy and Ultra2 bus segments until I get some? A: Yes. In fact, by connecting your standard Ultra wide devices to the card you obtain the equivalent of dual channel performance, with each bus segment at a 3 meter length limit and speeds to 40MB/sec. Q: What cables are included with the kit? A: The kit contains four cables: a SCSI-2 Wide 68-pin 3 connector ribbon cable, a SCSI-2 50-pin 3 connector narrow cable, a 5 connector Ultra2 Wide terminated cable, and an internal-to- external 50-pin Ultra cable with two additional internal connectors. Q: What is the purpose of the internal-to-external cable if I can use the external connector on the adapter? A: The external connector on the adapter is primarily designed for Ultra2 devices, so adding a standard Ultra device, to a configuration which already uses an external Ultra2 device, may create problems with termination and cable length. The internal-to-external cable provides the solution to using external SCSI-2 devices, like scanners or removable drives, on the SCSI Card 2940U2W, by routing the SCSI Ultra narrow port to a bracket mounted high density 50-pin external connector. The additional connectors on the cable allow the use of two internal SCSI-2/Fast/Ultra narrow devices, such as a narrow hard drive, CD-ROM, or tape drive. Q: Does the external connector on the internal-to-external cable require termination? A: YES!. If the internal-to-external cable is installed, the external high density connector must be connected to a single-ended SCSI-2 terminator or to a terminated peripheral at all times for proper adapter operation. The terminator is available through normal computer outlets or via Adaptec Sales. Q: Does Adaptec have cable kits available for the SCSI Card 2940U2W? A: Cable kits are available for the standard SCSI-2 cables. Cable kits for Ultra2 cables will be available after February 16, 1998. The part numbers and descriptions are: External cable kit ACK-H2H HD50 to HD50(1 Meter) ACK-H2L HD50 to Centronics ACK-W2W-E HD68 to HD68 (SCSI-2) ACK-U2W-1M HD68 Ultra2 (1 Meter) ACK-U2W-3M HD68 Ultra2 (3 Meter) ACK-68-TERM HD68 Ultra2 Terminator (LVD only, not for SE operation) ACK-50-TERM HD50 Ultra Terminator (SE only, active termination) Internal cable kit ACK-INT3-PNP 3 position 50-pin ribbon (2 devices + host, PnP compatible, terminated) ACK-INT5-PNP 5 position 50-pin ribbon (4 devices + host, PnP compatible, terminated) ACK-W2W-5I 5 position 68-pin ribbon (4 devices + host) ACK-W2W-5IT 5 position 68-pin ribbon (4 devices +host, PnP compatible, terminated) ACK-50I-50E(98) 50 pin internal ribbon to HD50 external connector with 3 internal connectors (2 devices + host) (for AHA-2940U2W only) ACK-68I-68E 68 pin internal ribbon to HD68 external connector (no internal device connectors) ACK-68I-U2W 5 position HD68 Ultra2 terminated Q: How do I set the burst transfer rate for SCSI devices? A: The maximum transfer rate is set in the SCSI Select Utility, Configure/View Host Adapter Settings, SCSI Device Configuration option. The transfer rate is set by selecting the transfer speed, hitting "enter", and then selecting the desired transfer rate. Q: Does the SCSI Card 2940U2W support SCAM (SCSI Configured AutoMatically)? A: The initial release of the SCSI Card 2940U2W BIOS, Version 2.0, does not support SCAM. This feature will be included in a future revision of the BIOS. Q: How can I tell if my SCSI device is connected to the proper bus segment? A: The internal Ultra2 connector is labeled as Ultra2 LVD/SE. The Ultra2 LVD/SE internal cable matching connector is also labeled. Ultra2 LVD devices are also labeled with the designation "LVD/SE". The BIOS scan on boot and the SCSI Select Utility also display the device and the bus segment. Example: (x is SCSI ID set on the device) SCSI SE hard drive on the legacy bus is identified as: SCSI ID:x vendor/model Fast/Ultra-SE Disc 0 Ultra2 LVD drive on the LVD/SE bus is identified as : SCSI ID:x vendor/model Ultra2-LVD Disc 0 SCSI SE hard drive on the LVD/SE bus is identified as: SCSI ID:x vendor/model Ultra2-SE Disc 0 Q: Can I mix wide and narrow devices on the LVD Ultra2 external bus segment? A: Since the initial introduction of LVD devices will be wide HDD assemblies, connecting wide and narrow devices externally assumes that SE legacy devices will be used. This will make the bus segment act as a single-ended Ultra bus with the same cable length, transfer speed, and termination requirements. A single-ended 68 to 50 pin converter with the upper byte actively terminated must be used on the last wide device, and then the narrow devices daisy-chained, with the last narrow device actively terminated. Q: Is it necessary that the last SCSI device on the cable is terminated? A: Yes. Improper termination on the host adapter or SCSI bus segment may cause the card not to initialize and the driver may fail to load.