home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Top Secret 12
/
Top Secret 12.adf
/
pages
/
1mbon
/
1mbon
Wrap
Text File
|
1991-08-15
|
2KB
|
66 lines
³¼1 MB ON THE BOARD¼³
¹
For those who haven't got themsel-
ves a ram-expansion yet, I've written
this article on how to get one MB on
the board. First you have to buy 4 ram
chips (1 Mbit, 256K*4, below 100 ns).
The best you can buy is of course those
with lowest ns-rate. The name of the
chips may be ex. 44256 (100 ns),
514256P (80 ns) or 64256-10 (70 ns).
Ask at your local shop. They'll cost
about 60-70 Dkr each. You shouldnt
forget to buy four 20-pin socket, if
you wont solder on the chips (bad
idea). If you want decoupling-capaci-
tors too, buy some normal capacitors
(330 nanofarad), NOT electrolyt. I'm
not quite sure if it is important to
have them on the board, but i f you
wanna be 100% sure, buy 4 of them.
After you've returned from the shop,
it's time to mount the sockets. You
first have to desolder all 80 holes
so the chips will fit in. You should
desolder hole at U20-23 and the
holes for the capacitors too. It's of
course necessary to take the hole
board up. When you've soldered the
sockets in the holes and soldered the
capacitors too, it's time to mount the
chips in the sockets. But you are not
finished yet. The Amiga dont know the
chips has been installed, so we have to
tell it first. Find jumper 2 which is
located near to the 68000-processor.
Cut the track between the two
pads. Now solder a wire from each pad
to a 2 poled on-on switch, making
sure that there's NO connection between
any of the pads. Now find jumper 7A,
which is located next to the ram-expan-
sion connector. As before cut the
track and solder the wires to the
switch. Now you've got a switch which
shifts between 1 MB of chipmem or
1/2 MB chipmem and 1/2 MB of fastmem.
If you want a switch that can turn
on and off the 1/2 MB fastmem (ofcourse
not in 1 MB chipmem-mode), you
should solder a wire to each pad on
jumper 7A (if you haven't done it be
fore, cut the track). The wires should
now be soldered to a 1 pole on-on
switch. And this is it.
³ The technical Mailbox
Co. Jacob Blichfeldt
Langelandsvej 1A
7400 Herning
Denmark