Panel H: Instruction Unit: Interrupt Control and Manual Control
The set of imprecise overflows DCML OFLO onwards at the top normally cause a change to the 8-byte PSW (Program Status Word)
that is indicated here. Bits 16 to 31 indicate the type of interruption:
16 STOR PROT Protection
17 ADR Addressing
18 SPEC Specification (not used on 360/195)
19 DATA Data
20 FXP OFLO Fixed-Point Overflow
21 FXP DIV Fixed-Point Divide
22 EXP OFLO Exponent Overflow
23 EXP UFLO Exponent Underflow
24 SGNF Significance
25 FLP DIV Floating-Point Divide
26 DCML OFLO Decimal Overflow
27 DCML DIV Decimal Divide
An External interruption (EXTERNAL CAPTIVITY/IDENTITY) occurs as the result of certain asynchronous events:
TIMER Timer
KEY Interrupt Key
2-7 External Signal 2-7
Below the Interrupt Controls on the left are displayed the contents of the PSW.
0-7 System Mask Bits 0 to 5 enable channels
Bit 6 for Channels 6-13
Bit 7 enables external interruptions (EXT SGL)
8-11 Protection Key PROTECT KEY
12 ASCII mode enable ASCII mode for packed decimal instructions
13 Machine checks enable Machine check interruptions
14 Wait State processor is halted
15 Problem state enable to prevent the use of instructions reserved for supervisor state
16-31 Interruption Code code to indicate the type of interruption
32-33 Instruction Length Code INSN LENGTH length in halfwords or 0 if unavailable
34-35 Condition Code CND CODE
36-39 Program Mask enables the four interrupts
40-63 Instruction Address
