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PDP11: Fixed spurious interrupt when setting GO

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The code wasn't handling interrupts correctly when TCCM was written. In
particular, if the GO bit clears DONE, the code looked for the "SET IE" case
too soon and didn't clear the interrupt that was incorrectly generated.
The new code factors "GO" into the calculation.
This commit is contained in:
Bob Supnik 2017-03-14 09:59:14 -07:00 • committed by Mark Pizzolato
parent aef66264de
commit e7a38cc56f
1 changed files with 5 additions and 3 deletions
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8
PDP11/pdp11_tc.c
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@ -1,6 +1,6 @@
/* pdp11_tc.c: PDP-11 DECtape simulator
Copyright (c) 1993-2016, Robert M Supnik
Copyright (c) 1993-2017, Robert M Supnik
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
@ -25,7 +25,8 @@
tc TC11/TU56 DECtape
04-Dec-13 RMS Revised to model TCCM correctly (Josh Dersch)
14-Mar-17 RMS Fixed spurious interrupt when setting GO (Paul Koning)
04-Dec-16 RMS Revised to model TCCM correctly (Josh Dersch)
23-Oct-13 RMS Revised for new boot setup routine
23-Jun-06 RMS Fixed switch conflict in ATTACH
10-Feb-06 RMS READ sets extended data bits in TCST (Alan Frisbie)
@ -504,7 +505,8 @@ switch (j) {
data = (PA & 1)? ((tccm & 0377) | (data << 8)): ((tccm & ~0377) | data);
if ((data & CSR_IE) == 0) /* clearing IE? */
CLR_INT (DTA); /* clear intr */
else if ((tccm & (CSR_DONE|CSR_IE)) == CSR_DONE) /* setting, DON'IE = DON? */
else if (((tccm & (CSR_DONE|CSR_IE)) == CSR_DONE) && /* set IE, DON'IE = DON? */
((data & CSR_GO) == 0)) /* and not setting GO? */
SET_INT (DTA); /* set intr */
tccm = (tccm & ~CSR_RW) | (data & CSR_RW); /* merge data */
if ((data & CSR_GO) != 0) { /* GO (DO) set? */