LSI 53C810A Prefetching Scripts Instructions, Sdms Software The Total Scsi Solution

Models: 53C810A

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A complete set of development tools is available for writing custom drivers with SCSI SCRIPTS. For more information on SCSI SCRIPTS instructions supported by the LSI53C810A, see Chapter 6, “Instruction Set of the I/O Processor.”

2.2.1 SDMS Software: The Total SCSI Solution

For users who do not need to develop custom drivers, LSI Logic provides a total SCSI solution in PC environments with SDMS software. SDMS software provides BIOS and driver support for hard disk, tape, and removable media peripherals for the major PC-based operating systems.

SDMS software includes a SCSI BIOS to manage all SCSI functions related to the device. It also provides a series of SCSI device drivers that support most major operating systems. SDMS software supports a multithreaded I/O application programming interface (API) for user-developed SCSI applications. SDMS software supports both the ASPI and CAM SCSI software specifications.

2.3 Prefetching SCRIPTS Instructions

When enabled by setting the Prefetch Enable bit (bit 5) in the DMA Control (DCNTL) register, the prefetch logic in the LSI53C810A fetches 4 or 8 Dwords of instructions. The prefetch logic automatically determines the maximum burst size that it can perform, based on the burst length as determined by the values in the DMA Mode (DMODE) register and the PCI Cache Line Size register (if cache mode is enabled). If the unit cannot perform bursts of at least 4 Dwords, it disables itself.

The LSI53C810A may flush the contents of the prefetch unit under certain conditions, listed below, to ensure that the chip always operates from the most current version of the software. When one of these conditions apply, the contents of the prefetch unit are automatically flushed.

On every Memory Move instruction. The Memory Move (MMOV) instruction is often used to place modified code directly into memory. To make sure that the chip executes all recent modifications, the prefetch unit flushes its contents and loads the modified code every time a MMOV instruction is issued. To avoid inadvertently flushing

Prefetching SCRIPTS Instructions

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LSI 53C810A technical manual Prefetching Scripts Instructions, Sdms Software The Total Scsi Solution