To build the device characteristics tables (DCT), HCD and IPL call all UIMs at initialization time. For each DASD device supported by the UIM, the UIM must build device characteristics parameters (DCP) and call the DCT build routine.

A UIM invokes the DCT build routine in 31-bit addressing mode, by using a BALR instruction. Use the standard register save area conventions. The address of the DCT build routine is in the field UCADCTP in the UCA.

DCT Build Routine Input Parameters

A UIM provides the input to the DCT build routine in the device characteristics parameters (DCP). The DCP resides in the UIM and is mapped by CBDZDCP.

Registers on Entry to the DCT Build Routine

Register 0

Undefined

Register 1

Pointer to a two-word parameter list

• Word 1 - Address of the UCA
• Word 2 - Address of the DCP

Register 2-12

Undefined

Register 13

Address of an 18-word save area

Register 14

Return address

Register 15

The DCT build routine entry point address

Registers on Exit from the DCT Build Routine

Register 0-15

Restored

Return Codes

None