Reselect Instruction

1.The LSI53C810A arbitrates for the SCSI bus by asserting the SCSI ID stored in the SCSI Chip ID (SCID) register. If it loses arbitration, it tries again during the next available arbitration cycle without reporting any lost arbitration status.

2.If the LSI53C810A wins arbitration, it attempts to reselect the SCSI device whose ID is defined in the destination ID field of the instruction. Once the LSI53C810A wins arbitration, it fetches the next instruction from the address pointed to by the DMA SCRIPTS Pointer (DSP) register. This way the SCRIPTS can move on to the next instruction before the reselection completes. It continues executing SCRIPTS until a SCRIPT that requires a response from the Initiator is encountered.

3.If the LSI53C810A is selected or reselected before winning arbitration, it fetches the next instruction from the address pointed to by the 32-bit jump address field stored in the DMA Next Address (DNAD) register. Manually set the LSI53C810A to Initiator mode if it is reselected, or to Target mode if it is selected.

Disconnect Instruction

The LSI53C810A disconnects from the SCSI bus by deasserting all SCSI signal outputs.

6-14

Instruction Set of the I/O Processor

Page 154
Image 154
LSI 53C810A technical manual Reselect Instruction, Disconnect Instruction