User Guide

Ampex 1308904-X4 Preliminary Draft 3-7
ACL Application Programmer’s Guide ACL Configuration
3.3.4 Product Information
You can use either the aclGetVersion() function or acl_query_library utility to retrieve
vendor-specific information from the ACL. The information includes: vendor name, product
name, software revision levels, and software release dates.
3.3.5 Multiple Port and Multiple Initiator Considerations
The two SCSI ports on the ACL system I/O panel are functionally equivalent. Each port is
independently addressable and neither port has priority over the other. If desired, you can
connect the ACL to two separate SCSI buses simultaneously and each SCSI bus can have
multiple initiators arbitrating in the standard way for access; e.g., using the aclReserve() and
aclRelease() functions to achieve coordination.
When an initiator makes a reservation, the ACL denies access to all other initiators regardless
of which bus they are on. In the absence of a reservation, commands can execute concurrently
on both buses. The ACL appears busy if two initiators issue tape cartridge access commands
simultaneously, however, and one of the commands is rejected. Unit Attention Conditions
notify initiators of mode parameter changes made by other initiators.
3.3.6 Configuration Parameters
Table 3-2 describes the ACL configuration parameters that set ACL behavior.
• To view the current parameter settings, use the aclGetParam() function or the
acl_getparam_library utility.
• To change a parameter setting, use the aclSetParam() function or the
acl_setparam_library utility.
The ACL keeps only one set of values for its configuration parameters and they apply to all
initiators in a multi-initiator SCSI configuration. The Save Page feature is not supported; after
a hard reset or power-up, all the mode parameters reset to their default values.
Writer_Note: How does the user application detect the Unit Attention that occurs asynchronously?
When any of the Mode Parameters change, the ACL generates a Unit Attention to all initiators
except the one that issued the change parameter command.