Privileged Operation - RCA 70/46 Reference Manual

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Q')
Priority No.
22
23
24
Condition
Privileged Operation
Operation Code Trap
Address Error
(Cont'd)
Table 9. Interrupt Conditions (Cont'd)
Flag Bit
221
222
2 23
Explanation
This interrupt occurs when a privileged instruction is attempted and the current
processor state is in non-privileged mode. (Bit position 15 of the Interrupt Status
register is set.) The instruction is suppressed. The privileged instructions in the
70/46 Processor are:
Diagnose
Start Device
Test Device
Halt Device
Check Channel
Program Control
Load Scratch Pad
Store Scratch Pad
Idle
Set Storage Key
Insert Storage Key
Write Direct
Read Direct
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If the Memory Protect option is installed.
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If the Direct Control option is installed.
This interrupt occurs when an operation code that is either not assigned or not avail-
able on the partiCUlar processor is attempted. No operation is performed. The instruc-
tion length code field of the P counter of the terminated state tells how far to
rollback the P-count to reach its value prior to interrupt as follows:
ILC
01
10
11
Length in Bytes
Two-bytes back
Four-bytes back
Six-bytes back
Note: The ILC is always generated from the operation code of the instruction.
Three conditions cause an address error interrupt to occur. They are: address error,
specification error, and protection error.
Addressing - An address error (addressing) interrupt occurs when:
1. An address specifies any part of data, an instruction or control word outside the
available main memory for the particular installation. The instruction operation
is terminated for an invalid data address, and the results of the instruction are
unpredictable. The instruction operation is suppressed for an invalid instruction
address.
2. An Execute instruction specifies another Execute instruction to be performed.
The operation is suppressed.
3. The first operand address field of an instruction designates an odd register
address for a pair of general registers that contain a double word operand. The
operation is suppressed.
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