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kickstart
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kickstart
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2022-11-05
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³¼KICKSTART-SWITCH¼³
¹
If you have an Amiga 500+ and are
tired of all the software who doesn't
run on kickstart 2.0 or if you want a
kickstart 2.0 in your old Amiga which
now runs on 1.3 here how to add a
switch who can shift between the two
ROM-chips. The solution is quite
simple. On every kickstart is a leg
called CS (chipselect). By pulling
this signal low, the chip is selec-
ted. The easiest to do, is to shift
the legs (in one position it is the
1st kick which is connected to the soc-
ket, in the other position it is the
2nd kick which is connected). What to
do: First pick out the kickstart which
is located close to the 68000-proces-
sor. Now bend leg 10 (CS), solder a
wire to it (and the 'hole 10' in the
socket), and put the chip back. Now
you take the new (or old) kickstart and
as on the other, bend leg 10. The
new chip should be pressed on the to
of the other (notice direction), so the
leg 1 on the new chip are on the top of
leg one on the old chip ! You should
now solder each leg 1-1 2-2 3-3 etc.
together exept leg 10 on each chip
(they must NOT touch each other). You
should now solder the wire from the
socket to the middle pin on an on-on
switch. The on of the two other wires
should be soldered to the upper pin on
the switch and the last wire to the
lower pin on the switch. Thats
(nearly) it. As I'm almost sure that
the kickstart is a tri-state chip,
it's important that you do the follow
ing. Find leg 21 on the kickstart
chips. Solder two 1 Kohm resistors to
the leg and on to each leg (10).
These resistors should force the leg
to go high when not selected. And
THATS it. I've seen some other ways of
making this switch. Some uses leg 12
(RemEN) and it maybe works but is not
a good idea to use. Why ? Because, if
the chipselect-signal goes high, the
RomEnable-signal will also go high and
tell the Gary that there's NO
kickstart. This means that the CS con-
trols the RomEN-signal, not oppo-
site. I even saw a kickstart-switch in
a danish magasine called Amiga-Maga-
sinet where Henrik Munch wrote that
leg 11 should be used to shift be
tween the chips. I do not know what
leg 11 is but I tried it and it did
NOT work (I think it is ground or some
thing). Nice article anyway.
³ The technical Mailbox
Co. Jacob Blichfeldt
Langelandsvej 1A
7400 Herning
Denmark