LSI LSI53C896, Technical Manual

Page: 163 / 370

SCSI Registers 4-51
SEM Semaphore 4
The SCRIPTS processor may set this bit using a
SCRIPTS register write instruction. An external processor
may also set it while the LSI53C896 SCSI function is
executing a SCRIPTS operation. This bit enables the
SCSI function to notify an external processor of a
predefined condition while SCRIPTS are running. The
external processor may also notify the LSI53C896 SCSI
function of a predefined condition and the SCRIPTS
processor may take action while SCRIPTS are executing.
CON Connected 3
This bit is automatically set any time the LSI53C896
SCSI function is connected to the SCSI bus as an initiator
or as a target. It is set after successfully completing
selection or when the LSI53C896 SCSI function responds
to a bus-initiated selection or reselection. It is also set
after the SCSI function wins arbitration when operating in
low level mode. When this bit is cleared, the LSI53C896
SCSI function is not connected to the SCSI bus.
INTF Interrupt-on-the-Fly 2
This bit is asserted by an INTFLY instruction during
SCRIPTS execution. SCRIPTS programs do not halt
when the interrupt occurs. This bit can be used to notify
a service routine, running on the main processor while
the SCRIPTS processor is still executing a SCRIPTS
program. If this bit is set, when the
Interrupt Status Zero
(ISTAT0) register is read it is not automatically cleared. To
clear this bit, write it to a one. The reset operation is
self-clearing.
Note: If the INTF bit is set but SIP or DIP is not set, do not
attempt to read the other chip status registers. An
Interrupt-on-the-Fly must be cleared before servicing any
other interrupts indicated by SIP or DIP.
This bit must be written to one in order to clear it after it
has been set.
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