Instruction manual

Page 20 Chapter Five
Eagle 250 Upgrade Instructions, Rev. A00
New Queue Block Requirement = 200 + (13 x 50)
This example results in a setting of 850 queue blocks. However, we strongly recommend that you
use a minimum a 2,500 queue blocks, even if the formula results in a lower number.
5. Since you will be booting from a SCSI disk drive connected to the AM-138-10 board, you need
to define the SCSI dispatcher for the Eagle 250 (described in Chapter 3) in the system
initialization command file. Add this command to the INI file after the JOBALC statements, but
before the first DEVTBL statement:
SCZDSP SCZ138.SYS
For example:
:T
JOBS 1
JOBALC JOB1
;
TRMDEF TERM1,AM318=0:19200,AM62A,100,100,100,EDITOR=15
VER
SCZDSP SCZ138.SYS/ET
;
DEVTBL DSK
The SCZ138 dispatcher supports several option switches, as shown in the following table:
Switch Description
/ET Enable tolerant active negation
/EW
/EW:{id#}
Enable Wide SCSI negotiation for all devices
Enable Wide SCSI negotiation for SCSI device ID#
/NQ
/NQ:{id#}
Disable Command Queuing for all devices
Disable Command Queuing for SCSI device ID#
/NS
/NS:{id#}
Disable Synchronous Negotiation for all devices
Disable Synchronous Negotiation for SCSI device ID#
/NP Disable Parity Checking (Parity still generated) on all devices
Table 5-1: Dispatcher Switch Table
We recommend that all Eagle 250s use the /ET switch (as shown above) to enable tolerant active
negation. Using active negation improves bus integrity when using synchronous data transfers.
Never attach a device to or remove a device from the SCSI bus while system power is
on. This is never a good idea, but active negation makes it even more likely that doing so
will damage the device, the SCSI controller, or both.
The most common of the other switches is /EW, to enable Wide SCSI operation when using the
optional Wide SCSI bus. If you have both Wide and narrow SCSI devices attached to the Wide
bus, enable Wide SCSI operation only for the Wide devices. For example, if you have a Wide
SCSI disk drive at SCSI ID 0 of the Wide bus, and narrow devices at other IDs, enter this
statement to enable Wide SCSI operation for just that drive:
SCZDSP SCZ138/ET/EW:0