Xerox 550 Reference Manual page 45

Table 3. Summary of Trap Locations (cont.)
Locations
PSWs
Dec. Hex.
Function Mask Bit Time of Occurrence
Trap Condition Code
72
48
CALLl None At instruction decode.
Equal to R field of
CALL instruction.
73 49 CALL2 None
At instruction decode. Equal to R field of
CALL instruction.
74 4A CALL3 None
At instruction decode. Equal to R field of
CALL instruction.
75 4B CALL4
None
At instruction decode. Equal to R field of
CALL instruction.
76 4C Hardware error trap None At time of basic processor detec-
TCC1, 2, 3
=
0
tion (the PDFt flag wi
II
be set).
TCC4
=
0 if parity
error on general reg-
ister or internal con-
trol regi ster
TCC4
=
1 if other
hardware errors.
77 4D Instruction exception trap None (The PDFt flag wi II be set.) Set TCC3 if MMC
configuration illegal;
set TCC
=
X'C'
if
trap or interrupt se-
quence with illegal
instruction;
set TCC
=
X'F' if
trap or interrupt se-
quence and processor
detected fau
I
t;
I
set TCC4 if !nvalid
register designation
{odd register on AD,
SD, FAL, FSL, FML,
FDL.
78 4E Reserved
79 4F Reserved
I
80 50 Power on Interruptible point.
81 51 Power off Interruptible point.
tSee "Processor Detected Faults", later in this chapter.
38 T rap System