User`s manual

SIOP Firmware Structures
B-18 Single Board Computers SCSI Software UserÕs Manual
B
siop_init (Firmware Initialization Structure)
This is the data structure passed to the siop_init() entry point.
typedef struct {
UINT signature /* MASK_INIT_1 | SCSI address of the SIOP */ 0x00
UINT intr_lev; /* level at which SIOP interrupt should occur */0x04
UINT sclk_speed; /* frequency of the SIOP clock (in Hz) */ 0x08
UINT snoopmode; /* snoop mode of processor */ 0x0c
RELC *reloctbl; /* pointer to scripts relocation table */ 0x10
UINT *script_ptr; /* pointer to script pointer array */ 0x14
} INIT_TYPE_1;
signature
The first 32-bit element represents a signature for the entire structure. This
allows firmware data structure definitions to be changed without breaking
existing source or binaries. In the case of the structure used for initialization,
the SCSI host address is encoded in the LSB of the signature.
The signature for an INIT_TYPE_1 structure is a bitwise-or of the preprocessor
define MASK_INIT_1 ('IT1\0') and the SCSI address of the SIOP.
intr_lev
The user initializes this field to the level (1-7) at which the SIOP is to interrupt
the MPU. For polled mode, in which the firmware does not relinquish the
processor until the command is complete, this field should be cleared. This
field is not checked for erroneous values. It is used directly to program the
PCC.
sclk_speed
This is the speed (in Hz) of the SCSI core clock feeding the SIOP. In the NCR
53C710 SIOP Data Manual, this clock is referred to as SCLK and it is used to
derive important timing information. The SCLK rate being fed into the SIOP
varies depending upon the system into which the SIOP has been designed.