Xerox 550 User Manual

Table 3. Summary of Trap Locations
Locations
PSWs
Dec. Hex.
Function
Mask Bit
Time
of Occurrence
Trap Condition Code
64 40
Nonallowed operation
l.
Nonexi stent
None
At instruction decode.
Set TCCl t
instruction
2.
Nonexistent mem- None
Prior to memory access.
Set TCC2
ory address
3.
Privi leged instruc- None
At instruction decode.
Set TCC3
tion in slave mode
4.
Memory protection
None
Prior to memory access.
Set TCC4
violation
5.
Write lock violation None
Prior to memory access.
Set TCC3, TCC4
65
41
Reserved
66 42
Push-down stack limit
TW, TS
At the time of stack limit detection. None
reached
(in stack
(The aborted pushdown instruction
pointer)
does not change memory, registers,
or the condition code.)
67
43 Fixed-point arithmetic
AM For all instructions except DWand
None
overflow
DH,
trap occurs after completion of
instruction.
For DW and DH, instruc-
tion is aborted with memory, register,
CC1, CC3, and CC4 unchanged.
68 44 Floating-point arithme-
At detection.
tic fault
l.
Characteristi c None
{ (The flooting-point instruction is
None
overflow
aborted without changing any reg-
2.
Divide by
zero None
isters. The condition code is set to None
3.
Significance check
FS, FZ, FN
indicate the reason for the trap. )
None
69
45 Reserved
70 46 Watchdog timer runout
None
At runout.
(The
PDFtt flag wi II be
Set TCC2 if basic
set. )
processor using
pro-
cessor bus;
set TCC3 if basic
processor using mem-
ory bus; and
set TCC4 if basic pro-
cessor using DIO bus.
71
47 Programmed trap
None
Interruptible point reached upon None
completion of WD.
tSee IITrap Condition Code
ll
, later in this chapter.
ttSee IIProcessor Detected Faults
ll
, later in this chapter.
Trap System 37

Xerox 550 Specifications

General

Brand	Xerox
Model	550
Category	Printer
Language	English