Force Computers PENT/CPCI-721, Installation Manual

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SCSI BIOS Features
PENT/CPCI-721 5 - 5
Selectable Settings For Synchronous Data Transfer
Synchronous data transfer is faster than asynchronous data transfer:
• If the adapter is set not to negotiate for synchronous data transfer,
the value to be selected will be the maximum rate at which the
adapter accepts data from the device during negotiation. This is
standard SCSI protocol. The values displayed assume that UltraSCSI
support is enabled (see the respective advanced configuration
option shown below). If not, the speeds are half those shown.
• Most SCSI devices support synchronous negotiation. If a device
does not support synchronous negotiation, the adapter will auto-
matically transfer the data in asynchronous mode.
• Specification of the maximum sync transfer rate: The maximum syn-
chronous data transfer rate determines the rate that the adapter
negotiates with the device. The adapter automatically negotiates for
the rate requested by the device.
• Sync negotiation: Synchronous negotiation is a SCSI feature that
allows the SCSI adapter and its attached SCSI devices to transfer
data in synchronous mode. The setting determines whether the
adapter initiates synchronous negotiation with the SCSI device.
However, the adapter always responds to synchronous negotiation
if the SCSI device initiates it. If neither the adapter nor the SCSI
device negotiates for synchronous data transfers, data will be trans-
ferred in asynchronous mode.
Enabling Disconnection
Enabling disconnection allows a SCSI device to disconnect from the
SCSI bus (sometimes called Disconnect/Reconnect). It allows the
adapter to perform other operations on the SCSI bus while the SCSI
device is temporarily disconnected. The SCSI device may choose not to
disconnect, however, even if permitted by the adapter (this can usually
be configured on the SCSI device). Leave this option set to yes if the
adapter connects to two or more SCSI devices. This optimizes SCSI bus
performance. If the adapter connects to only one SCSI device, set enable
disconnection to no to achieve slightly better performance.