My B doesn't work at 20/40 ?

From: Douglas Little <dmlittle_at_compuserve.com>
Date: Tue, 28 Oct 1997 14:59:14 -0500

Hi,

> As doug told me, i have made some few
> tests, and i saw that my AB was not
> working at 40 Mhz.

33MHz processors usually either work fine
or they work for a bit and then start to flake
out. 40MHz processors generally just work.

If your machine crashes 100% of the time
when you change to 40MHz then something
else may be wrong.

> I had set a 560 Ohm resistor betwin the
> white wire and the pin 5 of IKBD.

Did you keep the black wire grounded?

> Then i made some tests:
> AB is working correctly with the old
> drivers (ab40 mmu and ab40 fpu and also
> fafa16). but i tried to launch NemLO and

You shouldn't have to test it with the old drivers.

They don't work with most cards anyway,
especially FAFA16 which is hardwired for just
one of the AB card revisions.


> then the falcon crashed: 2 bombs and
> following message:
> out of internal memory:
> use foldr100.prg to get more.
> system halted

It could be the switching that is causing all
of the trouble.

BTW, who fitted the Nemesis card? It is
possible that the changes marked in the
addendum have not been applied to the
Nemesis card and buffer. The revision #2
boards need to have 2 of the electrolytic
capacitors removed to allow the switching
to work properly. If the card was fitted for
you, this SHOULD have been done already.

If you fitted the card yourself, you may not
have done this part.

If the card is the older type however, you
should not need to do anything at all.

> it does the sam thing with foldr999 in
> my autofolder.

No, that won't help. :)

> I also tried with tk 4.09.
> when nemesis is set to 40 Mhz in the
> driver, i met the same type of errors.
> if i remove Nemesis at 40 option, then
> the driver work properly... Note that
> often, when i try to boot with tk4.09
> and nem at 40, the machine crashes if i
> try to set Data cache on.....

Hmmm.

> Whih TK5.07 (which was not working when
> nem was "physicaly" off) it never boot
> properly:
> ram check, bss logo, then crash.
> I always made thoses test without anythi
> ng else in the auto folder than the driv
> ers itselves (driver+6882.prg)

Well, I can't explain that. It always works
here. Remember you need NVDI to make
TK5.07 work properly, or you get smashed
icons and the machine crashes. It's all in
the TK docs.

BTW, the only reason TK4.09 works without
NVDI is because it employs a very very
dangerous hack which I removed for TK5.

> So it appears that my AB do not support
> Nem 20/40 Mhz frequency, at boot and after...

I'd say your problems might be a little bit more
fundamental. BTW, is your CPU 33MHz or
40MHz?

> If anyone has the solution !

Check the Nemesis card to see if it still has
3 capacitors on board, or just one. If it has 3
then you may have to remove the two near
the black and white switching wires.

Don't do anything until you have looked at
the card to see what has been done to it.

I also need to know which revision the card
is. The easiest way is if you tell me when you
got the card, and where you got it from.

Doug.
Received on ti. okt. 28 1997 - 23:01:00 CET