More commentary on stack overflow checking

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Jeff 2016-11-19 12:22:37 -08:00 committed by Jeff Parsons
commit 60a3061ccb

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@ -349,3 +349,14 @@ whereas mode 6 *does*; eg:
R0=001437 R1=154112 R2=000040 R3=000376 R4=160316 R5=153412
SP=000376 PC=022074 PS=000340 IR=000000 SL=000377 T0 N0 Z0 V0 C0
022074: 050666 177776 BIS SP,177776(SP)
I have to assume that the idiosyncrasies of stack overflow checking changed over time, because [Test 14](#test-14),
which predates the 11/45 and 11/70, expects this instruction:
TST -(SP)
to trap when SP is 150. That contradicts this newer test (ie, that TST should not cause an overflow
trap "BECAUSE TST IS A NON MODIFYING INST"). For this and other reasons, PDPjs now installs different
checkStackLimit() handlers based on the CPU model.