Operational Procedures; Transmission Procedure; Response Procedure - RCA 70/46 Reference Manual

OPERATIONAL
PROCEDURES
Transmission Procedure
Response Procedure
Multi-Processor Installation
• The following sections are furnished
to
illustrate typical operational
procedures when using the Direct Control feature. They are presented for
clarification only and are not meant
to
imply fixed and firm standards.
For a detailed description of the actual programming procedures, reference
should be made to the applicable reference manuals .
• User Program - (PI) The user program in Processing State (PI)
contains a Supervisor Call instruction with a Write Direct Interrupt Code.
In addition, it contains the following parameters required when interrupt
is effected to the operating system in processor state
(P3):
Data Byte (8-bit code)
Signal Byte (specifies processor (s) to which
Write Direct is addressed)
Return Address (for return
to
normal processing)
Operating System - (P
3)
The operating system accepts the Super-
visor Call Interrupt and issues a Program Control instruction to (P
2 ) .
In addition, the locations of the user parameters are saved, the processor is
set to the Privileged Mode and a change made from (P
3 )
to (P
2 ) .
Supervisor Call Routine - (PrJ) The Interrupt Weight is used to
branch to the Supervisor Call routine where the Supervisor Call Interrupt
Code is decoded and a branch is made to the required routine, in this case
the Write Direct routine. The Write Direct routine then performs the
following:
1. Checks to determine whether Write Direct instruction can be issued
or must be stacked in queue.
2. Fetches the user parameters.
3. Sets Write Direct instruction I-Field to the Signal byte, the Address
field to the Data byte, and the Return After Interrupt to the user
Return Address in (PI).
4. Executes Write Direct instruction.
5. If no acknowledgement is received, sets control in Acknowledge queue.
6. Set processor to non-privileged mode.
7. After interrupt, executes Program Control instruction and branch
to user return address in (PI) .
• Operating System - (P
3 )
The operating system accepts the Direct
Control Interrupt and issues a Program Control instruction to (P
2 ) .
In
addition, the processor is set to privileged mode and a change made from
(P
3 )
to
(P
2 ) .
Read Direct Routine - (PrJ) The Interrupt Weight is used to branch
to the Read Direct routine. The Read Direct routine then performs the
following:
1. Issues a Read Direct instruction to read the Data Byte.
2. Saves the Data Byte and the External Interrupt number (which
corresponds to the transmitting processor) for user Read Direct
processing.
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