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The on-board floppy controller is shipped with a jumper installed at J6, position 6, floppy enabled. If the floppy controller on the AHA-1742A is not used, this jumper should be removed. Only one floppy controller per EISA system can be enabled. The AHA-1740A/1742A/1744 has a jumper that can be changed. This is the jumper block labeled J4, near the external connector. This determines whether or not the AHA-1740A/1742A/1744 will provide termination power to the SCSI bus. By default, the jumper is installed and termination power is provided by the host adapter. In general, the host adapter should always supply terminator power. However, no more than five SCSI devices should be configured to supply terminator power to a single SCSI bus. EISA-to-Fast SCSI Host Adapter Hardware Installation SCSI Terminators The SCSI bus must be terminated correctly to ensure proper operation. Only the first and last device on the SCSI bus (cable) should have the terminating resistors installed. All other SCSI devices should have the terminating resistors removed. The following figure shows two examples of SCSI device connections to the AHA-1740A/1742A/1744 Host Adapter. Figure 2-1. SCSI Device Termination The AHA-1740A/1742A/1744 is a SCSI device, and has socketed on-board terminators that should be removed if both the internal and external host adapter connectors are used. These can be reinstalled at a later time, if desired. On the AHA-1740A/1742A remove the RN5, RN6 and RN7 terminators. On the AHA-1744 remove the RN2, RN4 and RN5 terminators. adaptec AHA-1740A/1742A/1744 The RN5, RN6 and RN7 terminators on the AHA-1740A/1742A are 150 ohm terminators. The RN2, RN4, and RN5 terminators on the AHA-1744 are 330 ohm terminators. If the terminators are removed and installed again in the AHA-1744, be sure to put the 8-pin terminators in the 8-pin sockets and the 10-pin terminators in the 10-pin sockets. All SCSI peripherals have a way to add or remove termination. On some devices terminating resistors must be installed or removed. On others, only a switch need be toggled. Consult the user manual for the particular SCSI device. SCSI Parity The AHA-1740A/1742A/1744 always generates SCSI parity. SCSI parity checking can be enabled or disabled via the EISA Configuration utility. If any attached SCSI device does not generate SCSI parity, then parity checking for that device should be disabled. SCSI ID All SCSI devices have a parameter known as SCSI ID. The valid values are: 0, 1, 2, 3, 4, 5, 6, 7 This parameter is changed via jumpers or switches on most SCSI peripherals. The SCSI ID of the AHA-1740A/1742A/1744 is 7 (highest priority) and can be changed via the EISA Configuration utility provided with the EISA system. The SCSI ID of the host adapter is almost never changed from 7. All attached SCSI devices must have a unique SCSI ID. If the AHA-1740A/1742A/1744 is set to standard mode, the boot SCSI disk drive must be set to 0. EISA-to-Fast SCSI Host Adapter Hardware Installation Physical Installation in the System The following steps should be followed to install the AHA-1740A/1742A/1744 into the system: 1. Turn OFF the power to the computer system. 2. Remove the system cover according to the directions of the computer manufacturer. 3. If only an external SCSI subsystem is used, no internal cabling is required. If an internal SCSI peripheral is used, install a 50-pin SCSI ribbon cable to the host adapter. This cable must be oriented correctly. Pin 1 of the SCSI cable is designated by a red strip. Multicolor 50-pin ribbon cables signify pin 1 with a brown color. Pin 1 on the host adapter 50-pin SCSI header is located on the left- hand side, farthest from the installation bracket and is designated by the words PIN 1 on the board adjacent to the header. After locating pin 1 on the host adapter and on the SCSI cable, carefully insert the connector located at the end of the long end of the cable into the host adapter connector. After ensuring that all pins are lined up and that the pin 1 orientation is correct, firmly seat the connector to the board. 4. After installing the SCSI cable, the host adapter can be installed in any one of the 32-bit slots available in the host computer. Some slots in EISA machines do not support EISA bus mastering. The AHA-1740A/1742A/1744 cannot be used in such slots. If the AHA-1740A/1742A/1744 is accidentally installed in such a slot, the EISA Configuration program will report an error. A different slot must be chosen for the AHA-1740A/1742A/1744. 5. If an internal SCSI device is to be used, it should be installed in the drive bays in accordance with the directions on the peripheral. The proper power supply must be connected to the SCSI peripheral device. adaptec AHA-1740A/1742A/1744 6. The 50-pin SCSI ribbon cable can now be attached to each SCSI device. Refer to the device’s installation instructions to ensure proper pin 1 orientation. Pin 1 orientation must be consistent throughout the system. Keep the ribbon...

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