30 Aug
2014
30 Aug
'14
6:04 p.m.
On 2014-Aug-30, at 1:36 PM, drlegendre . wrote:
Message from me of 2014 August 27 1:45:56 PM PDT.
Generally speaking yes. On system reset, some flip-flop on a PROM board would be set,
enabling the PROM and asserting phantom on the bus, to disable a RAM board so the PROM can
overlay it. Some subsequent action during boot would trigger the PROM board flip-flop off
and de-assert phantom so you now had full RAM available.
But the RAM boards are passive responders to the phantom signal, there's nothing
prohibiting a system design or PROM board design from reasserting phantom at a later time
under some program action.
Correcting myself .. JTM.
If that photo on your site is the actual instance which you are to receive then yes, they
look quite the same.
Except the 5 CTS switch blocks on the photo instance have reversed on/off positions to the
one I have (and from the manual).
I was just playing with the one here to get it working.
On Sat, Aug 30, 2014 at 2:49 PM, Brent Hilpert
<hilpert at cs.ubc.ca> wrote:
Earlier in the
thread:
Really, where? In this thread? Hmm.. don't see it. Nothing else
in the system should be asserting phantom so it shouldn't
matter whether the phantom jumper is installed, but you could remove it to
be sure. (Sec 1.7)
I was wondering about Phantom.. as yes, it does seem to duplicate the same
functions as banking. But it seems that Phantom is only used upon reset, or
power-up, to +temporarily+ overlay boot code which then "disappears" for
the remainder of the session once it's served its purpose and the phantom
line is released.
So then, asserting Phantom when the system is operating has no effect -
correct? It only acts after a reset event? It would be like the action of a
J-K lfip-flop - the J/K lines cannot change the state of Q on their own,
they only determine what value Q will take on the rising-edge of the next
clock cycle (the reset event, for phantom).
Do I have that right? > Going from what I'm seeing you may have to be
careful to note the
> open/closed orientation of the switches, as it appears the installed
> switches aren't always consistent with the config diagrams in the manual.
Yes, duly noted.. I saw that.
> I actually have the JTS version of that board
(same board marketed under a
> different name).
The board
I'm receiving is marked JTS on the rear.. so I guess we've got
the same
one!