Common IOPB Structures

Command Code

This field specifies the command to be executed. Particular values are noted for each of the individual commands.

Command Options

This field specifies operational parameters or options to be associated with the execution of the command. The following subfields are available for all commands:

Table 3-15. Command Options

Command Options

Offst

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0x01

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Interrupt Enable (IE)

When set, the controller interrupts the host upon completion of the command, using the normal interrupt level and vector located in the IOPB if no error occurred, or the error interrupt level and vector otherwise.

Return Status

This field contains the returned status for the command. Any non-zero value indicates an error.

Normal Completion Level / Vector

This field contains the VMEbus interrupt level and vector used by the controller to notify the host of a successful command completion. These values are ignored when a command is posted as a multiple completion.

Error Completion Level / Vector

This field contains the VMEbus interrupt level and vector used to return commands which complete with errors.

DMA Transfer Control Word

This field contains control information which governs the DMA transfer of data between the host and the controller. The following subfields are defined:

Table 3-16. DMA Transfer Control Word

DMA Transfer Control Word

Offst

15

14

13

12

11

 

10

9

 

8

7

6

5

 

4

3

 

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0x05

Reserved

 

DIR

 

TT

MT

 

 

 

 

Address modifier

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

71