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Re: NadaNet for the //c - just an idea

mdj wrote:

On Aug 26, 8:46 am, "Michael J. Mahon" <mjma...@aol.com> wrote:

magnusfalkirk wrote:

On Aug 25, 1:15 pm, "Michael J. Mahon" <mjma...@aol.com> wrote:

It doesn't help that my IIc and IIc+ schematics are all but unreadable...
-michael
AppleCrate II: An Apple II "blade server"!
Home page:  http://members.aol.com/MJMahon/
"The wastebasket is our most important design
tool--and it's seriously underused."



Michael,
you should have that copy of the //c schematic that I copied from
the //c Technical reference. If you can't find them I can always e-
mail you a second set.



Yes, I checked that and another set that Bill Garber emailed,
but I note that neither shows the PB circuitry.  So I'll have
to go with the "abstracted" PB schematic in the manual.


The main concern would be the propagation delay of the opto's - there
doesn't appear to be any RF suppression on the input side (he says,
looking at a IIc motherboard)


The good news is that it now appears that WRPROT will do the
job as long as the state machine is left in the "shift in
WRPROT" mode.


It's worked fine for me in the past, but then, I wasn't attempting to
use anywhere near the bandwidth nadanet requires (ie. flat out!)


Since software can't produce an annunciator pulse shorter than
4 cycles, and since the read routine tolerates up to +/-2 cycles
of variation, it should work fine.

Frankly, the issue now is whether anyone cares.  ;-)

I'm working on a new rev of NadaNet (3.0) with improved collision
detection--so far, it's catching everything I can throw at it!

If there are actual (as opposed to potential) users of NadaNet
that just *have* to use it on a IIc or IIc+, then that might
raise its priority.

If a bunch of adapters were required, there's the annoying issue
of each one needing a hard to find Dx-19 connector...


FWIW, while I was perusing schematics, I noticed that XDIR
(pin 4 on the 9-pin game port) is apparently a straight
logic level input, and would be much easier than a PB!


For that one though (I think, as I left my IIc manual in melbourne
this trip) you'd have to put the machine into mouse mode (whatever pin
that is) to disable the 556 timer that normally triggers the PDL
inputs


According to my schematics, that's not the case for XDIR, which goes
straight into the mux.  YDIR does share an input with the 556.

-michael

AppleCrate II: An Apple II "blade server"!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."