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PDP1, PDP8, PDP18B, PDP11: Fixed dt_seterr to clear successor states

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For the PDP11, this includes deferring the setting of DONE on an error, allowing RSTS V4 to work correctly.

There was a minor (possibly only theoretical) bug in dt_seterr as well.
dt_seterr is supposed to stop the drive. If the drive is accelerating, at
speed, or stopped, it works fine. But if the drive is decelerating, it did
not clear out the "successor" states. In theory, the drive could be in the
middle of reversing - that is, there are successor states of accelerating
(in reverse) and at speed. So the successor states need to be cleared,
or the drive won't actually stop.

The fifth DECtape controller (the PDP8's TD8E) is much simpler and
doesn't have the problem.
This commit is contained in:
Bob Supnik
2017-03-15 10:04:52 -07:00
committed by Mark Pizzolato
parent 1cd11f3464
commit 62879beb70
4 changed files with 13 additions and 3 deletions
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8
PDP11/pdp11_tc.c
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@@ -25,6 +25,7 @@
tc TC11/TU56 DECtape
15-Mar-17 RMS Fixed to defer error interrupts (Paul Koning)
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
@@ -1049,7 +1050,9 @@ return SCPE_OK;
/* Utility routines */
/* Set error flag */
/* Set error flag
Done must be deferred to allow time for interrupt setup (RSTS V4)
*/
void dt_seterr (UNIT *uptr, int32 e)
{
@@ -1058,7 +1061,7 @@ int32 mot = DTS_GETMOT (uptr->STATE);
tcst = tcst | e; /* set error flag */
tccm = tccm | CSR_ERR;
if (!(tccm & CSR_DONE)) { /* not done? */
DT_SETDONE;
sim_activate (&dt_dev.units[DT_TIMER], dt_ctime); /* sched done */
}
if (mot >= DTS_ACCF) { /* ~stopped or stopping? */
sim_cancel (uptr); /* cancel activity */
@@ -1067,6 +1070,7 @@ if (mot >= DTS_ACCF) { /* ~stopped or stopping?
sim_activate (uptr, dt_dctime); /* sched decel */
DTS_SETSTA (DTS_DECF | (mot & DTS_DIR), 0); /* state = decel */
}
else DTS_SETSTA (mot, 0); /* clear 2nd, 3rd */
return;
}