Privileged Instructions; Interrupt Action - RCA 70/46 Reference Manual

PRIVILEGED
INSTRUCTIONS
INTRODUCTION
INSTRUCTION
FORMATS
RII
Format
De~wription
De~wription
SS Format
• The instructions described in this section are called privileged instruc-
tions and can only be executed if the non-privileged mode bit (bit position
15 in the Interrupt Status register) for the current state is zero.
In addition to the standard privileged instruction set, inclusion of the
memory protect and/or the direct control optional features cause additional
privileged instructions to be added.
Op Code
o
7 8 11 12 15
• The RR format is used only by the Set Storage Key and the Insert
Storage Key instructions. The contents of the general register specified
by the Rl field is the first operand. The general register specified by the
R2 field contains the second operand address.
o
7 8 15 16 19 20
31
• The SI format is used by the Program Control, the Write Direct, the
Read Direct instructions and all input/output instructions. The first address
(BdD 1 ) specifies the main memory location of the first operand. The
second operand js the immediate byte in the 12 field.
I
Op Code
I
L Bl
o
7 8 15 16 19 20 31 32 35 36 47
Description • The SS format is used by the Load Scratch Pad and the Store Scratch
Pad instructions. The location of the first operand is specified by the first
address (B1/D 1 ), and the location of the second operand is specified by
the second address (B 2 /D 2 ). The L field is the number of words in addition
to the addressed w'ord that are to be transferred.
INTERRUPT ACTION • The following interrupt conditions can occur as a result of a privileged
instruction:
Address Error
Addressing
• An address error interrupt occurs when an address specifies a location
outside the available main memory of the particular installation. The
operation is terminated at the point of error. The result data and condition
code, if produced, are unpredictable. If the address of an instruction is
invalid, the operation is suppressed.
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