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1991-08-15
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³¼TECHNICAL MAILBOX¼³
¹
Once again we hit you with a new tech-
nical Mailbox in this 12th issue of Top
Secret. We have got thousands of let
ters so it's nearly impossible to
answer all of them. NO, i have only got
1 letter (and another asking if i could
make the final list of indicators), so
the articles I wrote last time where
either too boring or just to easy to
understand. Anyway, let's take the
questions.
TSA/Cyborx writes:
²Hi Hawkeye!
I read your article about the level7
switch in Top Secret 11. I think your
modification is fine for the A500, but
for the A2000 (which I own), there's a
more elegant way to build an L7-switch
(atleast you dont have to solder any
wires directly to the MC68000): One
method is to connect pins 20 (GND) and
pin 40 (_EINT7) of the expansionport
via a switch. The other way is to use a
connector on the board. In my Amiga
(2000B-CR, rev 4.4), this connector has
the number CN606 and is on the left of
the MC68000 (if you look from the front
of the computer). This connector has
got 4 pins: IPL0-2 and GND! All you
need for an L7-switch! I think these
two methods are less dangerous for the
computer than soldering wires directly
to the processor.
¹
-ED: You got a point there !!! The
level7 switch in TS#11 was only
made for the Amiga 500, but its
great to see that you've got some
other ways to make it on an A2000.
²
TSA: Why do you place the LED between
+5v and the pin which gives you
the signal ? The LED shows you an
inverted signal !
¹
-ED: Sure it does. And we also wants it
to give an inverted signal because
all the signals I mention in my
article are active-LOW. That means
that the signal should be inverted
before showed !
²
TSA: Why do you use pin 78 on the Agnus
for the signal 'Joystick fires' ?
I think this is the Lightpen sig-
nal ?
¹
-ED: Arghh...Got me there. SORRY, a-
nother mistake !!! It is correct
that this is the lightpen-signal
which have nothing to do with the
joystick !!! Read the complete in-
dicators list to see the joystick
signal !
²
TSA: I think the indicators disk sa-
ves/load and writeprotected are
very useful. But, as I said, I own
and A2000 and I've got two built-
in drives. So, if I would use one
of the indicators, I wouldn't be
able to see which drive is meant.
Do you have a simple solution to
this ?
¹
-ED: Yep. Dont do anything !!! Why ?
Because the drives are ofcourse
not in use at the very same time.
So you can always watch the
load/save etc signal first and
then the drives signal. But if you
want a special signal to show
which drive is 'in action', use
the _SEL0&1-signals !
¹
Well thats all...This time I've inclu-
ded some kind of printerreset, the com-
plete indicators-list and some other
stuff, so read on !
By the way...I've just started on a
bigger project called 'Hardware Hea-
ven'. It'll be some kind of a diskmag
but with hardware-article ONLY !!! So
watch out for it (released middle sep-
tember). If you want the mag as soon as
it is finished, you may send me 2 chec-
ked disks (one for the mag and one for
postage), and I'll mail it to you. You
are also more than welcome to write
some articles for it !!! Or if you are
a graphician, what about painting some
hardware-clip arts ( medres 16 col max
100*250). Everything should be send to:
³ The technical Mailbox
Co. Jacob Blichfeldt
Langelandsvej 1A
7400 Herning
Denmark¹