Table A–6 (Cont.) SCB Layout
Vector
Name
Type
Parameter
Notes
48
CHMS
Trap
1
Parameter is sign-
extended operand
word
4C
CHMU
Trap
1
Parameter is sign-
extended operand
word
50
Unused
—
—
—
54
Soft error notification
Interrupt
0
IPL is 1A (hex)
58 to 5C
Unused
—
—
—
60
Hard error notification
Interrupt
0
IPL is 1D (hex)
64
Unused
—
—
—
68
Vector unit disabled
Fault
0
Vector instructions
6C to 80
Unused
—
—
—
84
Software level 1
Interrupt
0
88
Software level 2
Interrupt
0
Ordinarily used for
AST delivery
8C
Software level 3
Interrupt
0
Ordinarily used for
process scheduling
90 to BC
Software levels 4 to 15
Interrupt
0
—
C0
Interval timer
Interrupt
0
IPL is 16 (hex)
C4
Unused
—
—
—
C8
Emulation start
Fault
10
Same mode
exception, FPD=0;
parameters are
opcode, PC, specifiers
CC
Emulation continue
Fault
0
Same mode
exception, FPD=1;
parameters are
opcode, PC, specifiers
D0
Device vector
Interrupt
0
IPL is 14 (hex)
D4
Device vector
Interrupt
0
IPL is 15 (hex),
includes console
interrupts
D8
Device vector
Interrupt
0
IPL is 16
(hex), includes
interprocessor
interrupts
DC
Device vector
Interrupt
0
IPL is 17 (hex)
E0 to F4
Unused
—
—
—
F8 to FC
Unused
—
—
—
100 to
FFCC
Unused
—
—
—
A–12 Miscellaneous System Information