Fault Handling Action; Table 8-2. Fault Control Bits And Masks - Intel i960 Jx Developer's Manual

FAULTS
TC register trace mode bits and the PC register trace enable bit support trace faults. Trace mode
bits enable trace modes; the trace enable bit (PC.te) enables trace fault generation. The use of these
bits is described in the trace faults description in
Further discussion of these flags is provided in
Flag or Mask Name
Integer Overflow Mask Bit Arithmetic Controls (AC) Register INTEGER_OVERFLOW
No Imprecise Faults Bit
Trace Enable Bit
Trace Mode
Unaligned Fault Mask
The unaligned fault mask bit is located in the process control block (PRCB), which is read from
the fault configuration word (located at address PRCB pointer + 0CH) during initialization. It
controls whether unaligned memory accesses generate a fault. See
Transactions Across Region Boundaries" (pg.
8.8

FAULT HANDLING ACTION

Once a fault occurs, the processor saves the program state, calls the fault handling procedure and,
if possible, restores the program state when the fault recovery action completes. No software other
than the fault handling procedures is required to support this activity.
Three types of implicit procedure calls can be used to invoke the fault handling procedure: a local
call, a system-local call and a system-supervisor call.
The following subsections describe actions the processor takes while handling faults. It is not
necessary to read these sections to use the fault handling mechanism or to write a fault handling
procedure. These sections are provided for those readers who wish to know the details of the fault
handling mechanism.
8-16
section 8.10, "FAULT REFERENCE" (pg.
CHAPTER 9, TRACING AND

Table 8-2. Fault Control Bits and Masks

Location
Arithmetic Controls (AC) Register All Imprecise Faults
Process Controls (PC) Register
Trace Controls (TC) Register
Process Control Block (PRCB)
13-7).
DEBUGGING.
Faults Affected
All TRACE Faults
All TRACE Faults except hardware
breakpoint traces and fmark
UNALIGNED Fault
section 13.5.2, "Bus
8-21).