Interphase Tech CONDOR 4221 - Manual (Page 105)

Initialize Multiple Completions
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Initialize Multiple Completions
This command enables the controller to return multiple completed commands to the host with a single completion via
the Command Response Block, with a single (optional) interrupt.
When commands are completed using this mechanism, the returned IOPB is replaced with a substantially different
Multiple Completion Returned Command structure. Please refer to the system interface section of this chapter for
details.
Once the host has enabled multiple completions, the controller will still post back individually completed commands,
for any of the following conditions:
Only a single command required posting back (the multiple completion mechanism will never be used to post
back less than two commands)
The Disable Multiple Completion bit is set in a particular Transmit or Receive IOPB
The IOPB completed with error or exception. Such IOPBs will always be returned from the controller to the
host as a single completion.
When posting a group of commands as a multiple completion, the controller will ignore all interrupt related
information in the individual IOPBs, including the Interrupt Enable bit in the Command Options word, and the
interrupt level and vector, and will use the related fields provided in the Initialize Multiple Completions instead.
However, commands returned via the single completion mechanism will always use the interrupt information
contained in the individual IOPB.
The Initialize Multiple Completion IOPB must be issued through the Master Command Entry.
Table 3-34. Common IOPB Structures
Command Code
This field must be set to 0x80 to execute the Initialize Multiple Completions command.
Common IOPB Structures
Offst 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0x00 Command Code
0x01 Command Options
0x02 Return Status
0x03 Normal Completion Level Normal Completion Vector
0x04 Error Completion Level Error Completion Vector
0x05 Reserved
0x06 Control Flags
0x07 Group Interrupt Level Group Interrupt Vector
0x08 Minimum Group Count
0x09 Maximum Group Count