Loading...
1 Introduction
The Adaptec AHA®-2940Ultra and AHA-2940Ultra Wide PCI-to-Fast SCSI host adapters provide a powerful multitasking interface between your computer’s PCI bus and SCSI devices (disk drives, CD-ROM drives, scanners, tape backups, removable media drives, etc.). Collectively, both host adapters are referred to as the AHA-2940Ultra/2940Ultra Wide. The following figures show the major components on the AHA-2940Ultra and AHA-2940Ultra Wide.
50-pin 8-bit Internal |
Host Adapter |
|
SCSI Connector |
BIOS |
LED Connector |
Host
Adapter
LED
50-pin 8-bit External SCSI 
Connector
AIC-78xx SCSI Protocol Chip
Adaptec AHA-2940Ultra
68-pin 16-bit |
50-pin 8-bit Internal |
LED Connector |
||
Internal SCSI |
SCSI Connector |
|
|
|
Connector |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Host
Adapter
LED
68-pin 16-bit External SCSI Connector
Host Adapter
BIOS
AIC-78xx SCSI Protocol Chip
Adaptec AHA-2940Ultra Wide
1
2 Installing the Host Adapter
Follow these instructions to install the host adapter:
1Turn OFF power to the computer and peripheral devices and disconnect the power cords.
2Remove the cover from the computer case.
3Locate an unused 32-bit PCI expansion slot (the slot must support Bus Master data transfers); unscrew and remove the metal bracket that covers the card-slot opening. (Save the screw to use when securing the host adapter in your computer.)
PCI slots are shorter than ISA or EISA slots and are typically white. One of these may be a shared slot into which you can insert either an ISA/EISA board or a PCI board.
4Insert the host adapter in the PCI expansion slot. Press it down firmly so that the contacts are securely seated in the slot.
5When the host adapter is firmly seated in the expansion slot, secure the metal bracket of the host adapter with the screw you removed in step 3.
Do not replace the computer cover or reconnect your computer and peripherals to their power sources yet!
3 SCSI Configuration Guidelines
Before installing your SCSI devices, you should understand the basic SCSI concepts described in this section. The information will help you set up your host adapter and devices so they function properly.
SCSI ID Numbers
Each device attached to the host adapter, as well as the host adapter itself, must have a unique SCSI ID number (0 to 7 for the AHA-2940Ultra, and 0 to 15 for the AHA-2940Ultra Wide).
We recommend that you leave the host adapter set to its default setting of SCSI ID 7. If you need to change the host adapter SCSI ID, see Configuring the Host Adapter on page 7. To change the SCSI ID on
2
your hard disk and other SCSI devices, refer to the device’s documentation.
The host adapter supports the SCSI Configured AutoMatically (SCAM) protocol, which assigns SCSI IDs dynamically and resolves SCSI ID conflicts automatically at bootup. If your system includes SCSI disk drives or other devices that support SCAM, you do not need to manually assign SCSI IDs to these devices. To enable SCAM support, see Configuring the Host Adapter on page 7.
Most SCSI devices currently in use, however, do not support SCAM. The SCSI IDs on these devices must be set manually. To change the SCSI IDs on these devices, refer to the device’s documentation.
Note: If you plan to boot your computer from a SCSI device attached to the host adapter, set the Boot Target ID setting in the SCSISelect utility to correspond to the SCSI ID of the device you are booting from (see
Configuring the Host Adapter on page 7).
SCSI Terminators
To ensure reliable communication, the SCSI bus must be properly terminated. Termination is controlled by a set of electrical resistors, called terminators. Terminators must be placed (or enabled) at the two extreme ends of the SCSI bus. All devices that lie between the ends must have their terminators removed (or disabled).
Terminating the AHA-2940Ultra
Termination on the AHA-2940Ultra itself is controlled by software commands via the SCSISelectâ utility. The default setting is Automatic, which works like this:
■If the AHA-2940Ultra detects that a cable is connected to either its internal or external SCSI connector, then it enables its terminators (the AHA-2940Ultra is at the end of the SCSI bus).
3
■If the AHA-2940Ultra detects that a cable is connected to both its internal and external SCSI connector, then it disables its terminators (the AHA-2940Ultra lies between the ends of the SCSI bus).
We recommend that you leave the AHA-2940Ultra set to its default setting of Automatic. If you want to manually enable or disable the AHA-2940Ultra termination setting, see Configuring the Host Adapter on page 7.
Terminating the AHA-2940Ultra Wide
Termination on the AHA-2940Ultra Wide itself is controlled by software commands via the SCSISelect utility. The default setting is set to Automatic.
We recommend that you leave the AHA-2940Ultra Wide set to its default setting of Automatic. If you want to manually set the AHA-2940Ultra Wide termination setting, see Configuring the Host Adapter on page 7. The following table lists the termination settings for manual configuration.
|
AHA-2940Ultra |
|
|
Wide Termination |
|
Devices Connected to AHA-2940Ultra Wide |
Low |
High |
|
|
|
68-pin internal connector only |
ON |
ON |
68-pin external connector only |
ON |
ON |
68-pin internal and 68-pin external connectors |
OFF |
OFF |
50-pin internal connector only |
ON |
ON |
50-pin and 68-pin internal connectors |
OFF |
ON |
50-pin internal and 68-pin external connectors |
OFF |
ON |
|
|
|
Terminating SCSI Devices
Read the device’s documentation to determine how to enable or disable termination on your particular SCSI device(s). On most internal SCSI devices the termination setting is controlled by a jumper or a switch. On other internal SCSI devices you must physically remove or install resistor module(s). On most external SCSI devices, a terminating plug (a resistor pack embedded in a small plug) is installed or removed to control termination.
4
4 Installing SCSI Devices
You can connect up to a total of seven internal and external 8-bit SCSI devices to the AHA-2940Ultra, and up to 15 devices (seven 8-bit internal and eight Wide (16-bit) internal or external SCSI devices, or 15 Wide internal and external SCSI devices) to the AHA-2940Ultra Wide.
Note: You may only use two of the three connectors at any one time on the AHA-2940Ultra Wide host adapter.
Choosing SCSI Cables
The cables required to connect SCSI devices are determined by the type of devices you are installing, as described in the following table.
SCSI Device Type |
AHA-2940Ultra |
AHA-2940Ultra Wide |
8-bit Internal SCSI |
50-pin internal |
50-pin internal |
|
SCSI cable |
SCSI cable |
8-bit External SCSI |
50-pin high-density |
— |
|
external SCSI cable |
|
16-bit Internal |
— |
68-pin internal |
Wide SCSI |
|
SCSI cable |
16-bit External |
— |
68-pin external |
Wide SCSI |
|
SCSI cable |
|
|
|
If you purchased your AHA-2940Ultra/2940Ultra Wide in an Adaptec kit, the kit includes an internal SCSI cable that allows you to connect up to two internal SCSI devices (the AHA-2940Ultra kit includes a 50-pin internal SCSI cable, and the AHA-2940Ultra Wide kit includes both a 50-pin and a 68-pin internal SCSI cable). If you are connecting more than two internal SCSI devices, you must obtain an internal SCSI cable with enough connectors to accommodate all of your devices.
Adaptec sells high-quality internal and external SCSI cables. If your reseller does not stock these cables, you can order them directly from Adaptec.
When Fast SCSI devices are connected to the host adapter, the total length of all cables (internal and
5
Loading...