Avago Technologies LSI53C1010 - Manual (Page 191)

I/O Request Process 8-5
Figure 8.3 Power Up Examples
8.4 I/O Request Process
Figure 8.4 illustrates a typical SCSI I/O operation. The I/O begins when
the user application makes a request to the host operating system to
access data on a SCSI device. The request is passed to the SCSI device
driver's operating system interface where it is interpreted, scheduled, and
formatted for the hardware interface. The operating system interface
creates a data structure in host memory, which it passes to the hardware
interface layer for execution. The hardware interface uses the information
in the command block to determine which SCRIPTS routine to run, as
well as where to place the data in memory.
The hardware interface sets up the data areas for the command and data
buffers. These buffers are initialized table areas and buffers that are
needed for the SCRIPTS execution. It subsequently loads the SCRIPTS
starting address into the DSP register of the chip. The SCRIPTS
processor executes the subroutine, accessing the drive with the SCSI
Host Memory
55AA - Jump 0xC000
0xC2000
VGA Graphics BIOS
0xD800 55AA - Jump
SCSI Driver Initialization
- diagnostics
- load SCRIPTS instruction
- initialize SCRIPTS instruction
- reserve data buffer area
- scan for hard disk
- load operating system from disk
POWER UP System BIOS Scan