Adaptec 1520B User Guide - Page 10

SCSI Device Settings The SCSI device settings allow you to configure certain parameters for each device on the SCSI bus. To configure settings for a specific device, you must know the SCSI ID assigned to that device. If you are not sure of the SCSI ID, see Using the SCSI Disk Utilities on page 9. s Initiate Sync Negotiation-This option determines whether synchronous data transfer negotiation (Sync Negotiation) between the device and host adapter is initiated by the host adapter. Normally, the Initiate Sync Negotiation setting should be enabled, because most SCSI devices support synchronous negotiation and because it allows for faster data transfer. s Maximum Sync Transfer Rate-This option sets the maximum synchronous data transfer rate that the host adapter supports. The host adapter supports rates up to the Fast SCSI maximum of 10.0 MBytes/ sec. In most cases, you can use the maximum value of 10.0. s Enable Disconnection-This option determines whether the host adapter allows the SCSI device to disconnect from the SCSI bus (sometimes called Disconnect/Reconnect). If you have only one device on the SCSI bus, disabling disconnection will give a slight performance increase. If you have more than one device on the SCSI bus, disconnection should be enabled to allow multithreaded SCSI operation. s Send Start Unit Command-This option determines whether the Start Unit Command is sent to the SCSI device at bootup. Most devices do not require this, but check your device's documentation. Advanced Host Adapter Settings The advanced host adapter settings should not be changed unless absolutely necessary. s ISA Plug and Play Support-This option determines whether the host adapter supports Plug and Play functionality. When Plug and Play Support is enabled, the host adapter will work fine in both Plug and Play and Legacy (non-Plug and Play) systems. The only time you should disable Plug and Play Support is when you have an "ill-behaved" Plug and Play system. If you cannot get your host adapter working in a Plug and Play system, as a last resort, try disabling this setting. s Plug and Play SCAM Support-This option determines whether the host adapter automatically assigns SCSI IDs to SCSI devices that support the SCAM protocol (see Using Your Host Adapter on page 6). Most non-SCAM devices tolerate the SCAM protocol, so you can enable this option even if you have a nonSCAM device. s Host Adapter BIOS-This option enables or disables the host adapter BIOS functionality. Unlike the DIP switch BIOS PROM Disabled setting, when you disable the Host Adapter BIOS with SCSISelect, you still have access to SCSISelect. If you are booting from a SCSI disk drive connected to the host adapter, the BIOS must be enabled. Several SCSISelect options are not valid unless the host adapter BIOS is enabled. The table on page 8 identifies these options. You should disable the host adapter BIOS if the peripherals on the SCSI bus (for example, CD-ROM drives) are all controlled by device drivers and do not need the BIOS. s Support Removable Disks Under BIOS as Fixed Disks-This option controls which removable-media drives are supported by the host adapter BIOS. The following choices are available: - Boot Only-Only the removable-media drive designated as the boot device is treated as a hard disk drive. - All Disks-All removable-media drives supported by the BIOS are treated as hard disk drives. - Disabled- No removable-media drives are treated as hard disk drives. In this situation, software drivers are needed because the drives are not controlled by the BIOS. Caution: If a removable-media SCSI device is controlled by the host adapter BIOS, do not remove the media while the drive is on or you may lose data! If you want to be able to remove media while the drive is on, install the removable-media device driver and set this option to Disabled. 10 AHA-1520B Installation Guide Part Number: 511162-00, Rev. A Page 10 of 16 Print Spec Number: 495339-00 Current Date: 5/30/96 Last Modified: May 30, 1996 3:43 pm File Location: n:\mario\1520b_ig.nec\1520b_ig.frm ECN Date: 6/11/95 AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA