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Cleaned up the Front Panel address and data interfaces so that BOOTMON's "LIGHTS" test works as expected now

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Jeff 2016-11-09 12:46:03 -08:00 • committed by Jeff Parsons
commit 595c40e446
10 changed files with 401 additions and 366 deletions
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24
modules/pdp11/lib/cpuops.js
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@ -1756,7 +1756,7 @@ PDP11.opWAIT = function(opCode)
/*
* The original PDP-11 emulation code would actually stop emulating instructions now, relying on assorted
* setTimeout() callbacks, setInterval() callbacks, device XHR (XMLHttpRequest) callbacks, etc, to eventually
* call interrupt(), which would then transition the CPU of its "wait" state and kickstart emulate() again.
* call interrupt(), which would then transition the CPU out of its "wait" state and kickstart emulate() again.
*
* That approach isn't compatible with PCjs emulators, which prefer to rely on the simulated CPU clock to
* drive all simulated device updates. This means components should call the CPU's setTimer() function, which
@ -1780,21 +1780,21 @@ PDP11.opWAIT = function(opCode)
* check can have a measurable (negative) impact on performance. Which is why it's important to use opFlags bits
* whenever possible, since we can test for multiple (up to 32) exceptional conditions with a single check.
*
* Finally, we used to update the machine's displays whenever transitioning to the WAIT state. However,
* it makes more sense to decouple display updates from specific instructions and rely on timers instead;
* the PDP-11 KW11 (60Hz Line Clock) timer is the perfect candidate. See device.js.
* We also used to update the machine's display(s) whenever transitioning to the WAIT state. However, that
* caused this instruction to generate enormous overhead, and it's no longer necessary, since we now rely on
* a timer (the PDP-11's own KW11 60Hz Line Clock timer, to be precise) to generate periodic display updates.
*
* if (!(this.opFlags & PDP11.OPFLAG.WAIT) && this.cmp) this.cmp.updateDisplays();
*
* However, that being said, it's been reported that the WAIT instruction puts the contents of R0 into the
* Front Panel's "DATA PATH". However, I can't find any supporting documentation of that. Another explanation
* would be that the data path is being updated constantly, and that when R0 is the last register to be updated
* before a WAIT instruction, it simply predominates the data being displayed.
*
* But for now, we'll go with popular lore and propagate R0 to the Panel's "DATA PATH" setting.
* Finally, it's been noted several places online that the WAIT instruction puts the contents of R0 into the
* Front Panel's "DATA PATH" (and possibly even directly into the "DISPLAY REGISTER", making the DATASEL switch
* setting irrelevant). I can't find any supporting DEC documentation regarding this, but for now, we'll go
* with popular lore and propagate R0 to the panel's "active" data register.
*/
if (this.panel) this.panel.setDataPath(this.regsGen[0]);
if (this.panel) {
this.panel.setAddr(this.regsGen[7], true);
this.panel.setData(this.regsGen[0], true);
}
this.opFlags |= PDP11.OPFLAG.WAIT;
this.advancePC(-2);
this.nStepCycles -= 3;