MAS281 Dynex, MAS281 Datasheet - Page 16

• Manufacturer Part Number: MAS281
• Description: MIL-STD-1750A Microprocessor
• Manufacturer: Dynex

MAS281
3.6.2 USING BPT
instruction with Console present indicated in the Configuration
Word. On encountering a BPT instruction, the processor reads
the Configuration Word to check for the presence of a
Console. If a Console is indicated, the microsequencer
branches to the microcode BPT Hold service routine. This
routine decrements IC once, drops HLDAKN low, and enters
the Hold state.
HOLDN input must be pulsed low in accordance with the
timing diagrams in Section 6.0. When HOLDN returns high, the
Hold state will be released on the following SYNCN high-to-low
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The Hold state may also be entered by executing a BPT
To release the MAS281 from a BPT initiated Hold state, the
Figure 7: Pending Interrupt Register Bit Assignments
transition. The instruction pipeline is then refilled and
instruction execution resumes with the first instruction loaded
into the pipeline.
3.6.3 SINGLE-STEPPING
the HOLDN input and the BPT instruction. Use the BPT
instruction to mark the beginning of the section of code which
will be stepped through. Pulse HOLDN low to release the BPT
initiated Hold state and then pull HOLDN low again during the
two subsequent SYNCN cycles that refill the instruction
pipeline. When the first instruction following Hold release
completes execution, the module will once again enter the
Software can be single-stepped through the proper use of
Figure 8: Fault Register Bit Assignments