LSI53C825AJ LSI, LSI53C825AJ Datasheet - Page 186

• Manufacturer Part Number: LSI53C825AJ
• Manufacturer: LSI

Specifications of LSI53C825AJ

• Lead Free Status / RoHS Status: Not Compliant

5.2 High Level SCSI SCRIPTS Mode
5-2
To operate in the SCSI SCRIPTS mode, the LSI53C825A requires only
a SCRIPTS start address. The start address must be at a Dword (four
byte) boundary to align all the following SCRIPTS at a Dword boundary
since all SCRIPTS are 8 or 12 bytes long. Instructions are fetched until
an interrupt instruction is encountered, or until an unexpected event
(such as a hardware error) causes an interrupt to the external processor.
Once an interrupt is generated, the LSI53C825A halts all operations until
the interrupt is serviced. Then, the start address of the next SCRIPTS
instruction may be written to the
to restart the automatic fetching and execution of instructions.
The SCSI SCRIPTS mode of execution allows the LSI53C825A to make
decisions based on the status of the SCSI bus, which offloads the
microprocessor from servicing the numerous interrupts inherent in I/O
operations.
Given the rich set of SCSI-oriented features included in the instruction
set, and the ability to re-enter the SCSI algorithm at any point, this high
level interface is all that is required for both normal and exception
conditions. Switching to low level mode for error recovery should never
be required.
SCSI SCRIPTS Instruction Set
DMA SCRIPTS Pointer (DSP)
register