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wfjm.w11/doc/ECO-029-cpuerr_creset.md
wfjm 4001ddd695 docu updates; remove artys7 from tbrun.yml [skip ci] 
Closes #17
2022-04-20 12:33:00 +02:00

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ECO-029: CPUERR cleared by cpu reset (2016-12-27)

Scope

  • Was in w11a from the very beginning
  • Affects: all w11a systems

Symptom summary

  • the cpuerr register is not cleared by a $cpu cp -creset command
  • the cpuerr status can affect cpu behavior, e.g. yellow stack traps are only taken when the corresponding cpuerr flag is not set
  • this makes tbench test execution on FPGA potentially depending on pre-history

Fixes

Changed pdp11_sequencer.vhd to clear cpuerr with both general reset and with cpu reset.

Side effects

None because this affects a very early phase of system startup.