[HECnet] PDXVAX - 40MB Memory - VAXstation 4000/VLC?

[Brian Hechinger]

On Mon, Oct 19, 2009 at 07:17:18PM +0200, Johnny Billquist wrote:

You don't do DMA from CPU to a device. Remember what DMA stands for? :-)

Oh, duh.   I knew that.   I blame a lack of coffee. ;)

Hmm, I realized one thing, though. With a common Qbus, all interrupts 
will probably go to the bus master arbiter, which means that all devices 
actually must be attached to CPA, except such devices that are local to 
each CPU, such as the console terminal.

That solves that problem. :)

And in RSX speak, the CPUs are called CPA, CPB, CPC and CPD. Here is how 
it looks on MIM::

.con dis full att for sys
SYS         SYS         Online,Accpath
                              PDP-11/74mP, EIS,UNIBUS_Map,D-Space,SWR,Cache,FPP,
                              Clock=KW11-L, $TKPS=50., $TTPRM=000002
.con dis full att for cp
CPA         CPA         Online,Accpath
                              Cache_control=000001, Timer=Off, Alarm=Off
CPB         CPB         Offline,Accpath
                              Cache_control=000001, Timer=Off, Alarm=Off
CPC         CPC         Online,Accpath
                              Cache_control=000001, Timer=Off, Alarm=Off
CPD         CPD         Offline,Accpath
                              Cache_control=000001, Timer=Off, Alarm=Off
.con dis full att for du
DUA         CPA         Online,Accpath,Driver
                              Csr=172150, Vector=000154, Pri=000005, Urm=000001
DU0:       CPA     DUA0:         Online,Accpath,Context,Driver,Type=RZ29
DU1:       CPA     DUA1:         Online,Accpath,Driver,Type=RD53
DU2:       CPA     DUA2:         Online,Accpath,Driver,Type=RD52
DU3:       CPA     DUA3:         Offline,Accpath,Driver
DU4:                                       Online,Accpath,Context,Driver,Type=VRA82
.

Notice that CPA and CPC are online.
And DUA is attached to CPA, and so on...

That's nifty.   I can't wait to get mine setup. :)

-brian
-- 
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