00 HLT

Privileged Instruction

Halts the CPU6

The HLT instruction will check the current interrupt level. If the interrupt level is 15, then the CPU6 enters the Halt state which can be exited with a backplane interrupt or DMA interrupt, or by toggling the R or I dip switches. If the interrupt level is not 15, then HLT will trigger an abort trap with value 1.

Bugs

HLT does not Halt unless interrupt level is 15.

Pseudocode

If map level < 4 then
   if interrupt level < 15 then
      abort 1
   end else
      halt
   end if
end else
   abort 1
end if

Microcode

500       CRY0 r00 r00 RAM  NOT.D                 D D D      7b2 b2 (4d)                                                READ.MSR    (500)  ;* !CL
          CRY0 r00 r00 PASS NOT.D.AND.A           P P D      0f0 f0 (0f)          LOAD.FLR                              READ.CONST  (7b2)  ;* !CL & f0 (any bits are 1?)
          CRY0 r00 r00 Q    ZERO        COND Z    P P D      0c1 c1 (3e)          BUS.WAIT                              READ.SWP    (7b0)  ;* zero?
          CRY1 r00 r00 PASS Q+0                   D D D      105 05 (fa)                                       LOAD.RR  READ.SWP    (7b1)  ;* no - trap 1
7b3       CRY0 r00 r09 RAM  NOT.D                 D D D      71e 1e (e1)                                       LOAD.RIR READ.CONST  (7b3)  ;* yes - halt level 15