When I built this project I did not want to modify my C64c, So I installed two machined Pin IC-Sockets (18-PIN type) and soldered them to the C64 Motherboard, so i can still use two of the normal RAM chips if I desire.
To build the interface you need 3 things:-
(1) An IBM 30-PIN SIMM Socket (Can be de-soldered from any old 286,386, 486 etc..)
(2) 21 Wire Ribbon cable (I used an old 40 Wire IDE HD cable)
(3) Two 18-way Machined Pin IC Sockets. [Solder the 21-Wire Ribbon cable to this)
SIMM = Stands for SINGLE IN-LINE MEMORY MODULE.
These are mainly found in IBM Compatible Computers in sizes:-
286, 386, 486 = 30 PIN SIMMS
486, Pentium 1 = 72 PIN SIMMS
Pentium 2, Pentium 3 = 168 PIN SIMMS
Pentium 4, AMD64 = 184 PIN SIMMS