Acer Altos 500 Series User Manual page 94

Enable Disconnection
This option determines whether the SCSI controller allows a SCSI device to
disconnect from the SCSI bus (sometimes called Disconnect/Reconnect).
Disconnect/Reconnect allows the SCSI controller to perform other operations on
the SCSI bus while the SCSI device is temporarily disconnected.
When set to yes, the SCSI device may disconnect from the SCSI bus. The SCSI
device, however, may choose not to disconnect, even if permitted by the SCSI
controller (this can usually be configured on the SCSI device). When set to no, the
SCSI device is not allowed to disconnect from the SCSI bus. The default setting is
yes.
You should leave Enable Disconnection set to yes if two or more SCSI devices are
connected to the SCSI controller. This optimizes SCSI bus performance. If only one
SCSI device is connected to the SCSI controller, set Enable Disconnection to no to
achieve slightly better performance.
Initiate Wide Negotiation
This option allows communication between all devices (lower 8-bit or upper 8-bit)
on the wide (16-bit) SCSI bus. When set to yes, each device can connect on the bus.
When set to no (disabled), communication can only occur on the lower 8-bits of the
16-bit SCSI bus. The default setting is yes.
Altos 500 Series User's Guide