Avago Technologies LSI53C1010 - Manual (Page 31)

SCSI SCRIPTS Processors 2-1
Chapter 2
Programming with
SCRIPTS
This chapter contains the following sections:
•
Section 2.1, “The SCSI SCRIPTS Processor,” page 2-1
•
Section 2.2, “SCRIPTS and the SCSI Bus Phases,” page 2-2
•
Section 2.3, “Assembling SCSI SCRIPTS,” page 2-3
•
Section 2.4, “Using SCSI SCRIPTS,” page 2-6
•
Section 2.5, “Big and Little Endian Byte Addressing,” page 2-8
2.1 The SCSI SCRIPTS Processor
The SCSI SCRIPTS processor permits instructions to be fetched from
internal or external memory. Algorithms written in the SCSI SCRIPTS
language are assembled to control the SCSI and DMA modules.
Complex SCSI bus sequences, including multiple SCRIPTS instructions,
execute independently of the host processor.
The SCSI SCRIPTS reside in host computer memory or internal
SCRIPTS RAM during system operation, allowing for fast execution. If
instructions reside in external memory, the chip fetches SCRIPTS
programs from memory using bus master DMA transfers. If instructions
reside in SCRIPTS RAM, they are fetched directly from RAM without
generating PCI bus traffic. The SCRIPTS processor allows you to fine
tune SCSI operations such as adjusting to new device types, adapting to
changes in SCSI logical definitions, or quickly incorporating new options,
such as vendor unique commands or new SCSI specifications. The
SCRIPTS processor fetches SCRIPTS instructions from system memory
to control chip operation. The SCRIPTS processor does not compile
code; SCRIPTS programs must be assembled for execution by the
NASM assembler and then compiled with a standard “C” compiler as part
of a “C” program. Third generation SCSI devices can be programmed