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Robert Armstrong wrote:
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<pre wrap="">On the other hand, TSS/8 seems to be calling unimplemented
instructions all the time. It stopped almost as soon as I ran
it with the above instruction.
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<pre wrap=""><!---->
TSS/8 uses unimplemented IOTs (i.e. 06xxx opcodes) as monitor calls. With
the PDP-8 User Mode flag set, _all_ IOTs trap to the OS whether the hardware
actually implements them or not, and the TSS/8 designers simply picked some
unimplemented IOTs as the official way to call monitor functions. Is that
what you're seeing??
Bob Armstrong
_</pre>
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Didn't TOPS 10 do somthing similar? I remember from long time ago when
I was doing MACRO-10 that system calls were UUO (Unimplemented User
Opcode) instructions.<br>
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