Retro/pcjs
Watch
1
0
Fork
You've already forked pcjs
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Revert back to propagating R0 to the Front Panel data path on a WAIT instruction (per PDP-11 lore)

Browse source
This commit is contained in:
Jeff 2016-11-08 14:21:07 -08:00 • committed by Jeff Parsons
commit f43d1c1745
7 changed files with 642 additions and 617 deletions
Download patch file Download diff file Expand all files Collapse all files

9
modules/pdp11/lib/cpuops.js
View file

@ -1785,7 +1785,16 @@ PDP11.opWAIT = function(opCode)
* the PDP-11 KW11 (60Hz Line Clock) timer is the perfect candidate. See device.js.
*
* 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.
*/
if (this.panel) this.panel.setDataPath(this.regsGen[0]);
this.opFlags |= PDP11.OPFLAG.WAIT;
this.advancePC(-2);
this.nStepCycles -= 3;