Notes on the 1541-II
The 6502 RAM/ROM expansion board can also be used in the 1541-II, if it
is built with special components, most importantly the low-profile
socket adaptors. Only with these a socket can be put into the 1541-II
board, otherwise you'd have to solder in the normal socket adaptor
directly! The ROM of the 1541-II has to be removed, because it is
always installed in a socket and would be in the way. Maybe you have to
shorten the wires of some chips or sockets
after soldering them, if they collide with underlying chips.
With these special low-profile socket adaptors, the expansion will even
fit into a 1541-II with the belt-driven Newtronics D500 mech, though
there is only about 1mm space left between them. With the other method
(direct soldering of the standard socket adaptor) there is no space
left, and you can't use the expansion in the belt-drive version. Ask me
for the low-profile version, I have a small stock of them and can
supply them for some extra price, together with the precision sockets
that you also need.
Of course, the two 6522 chips and the RAM chip cannot be installed in
sockets, as you can see in the pictures. A parallel cable has to be
soldered directly to the pins of the 6522, preferrably from the bottom
side, since you have to cut a trace there anyway.
Here are some pictures to illustrate the usage. You can click on them
to get the full size version.
Go back to: X1541.DE - Hardware Projects - 6502
RAM/ROM Expansion - Construction Page