For Multiplexer and Demultiplexer you need the TTL CMOS Digital ICs (74 LS Family). Here is five DataSheets... 1. 74 151 2. 74 LS 138 (FairChild) 3. 74 LS 138 (ON Semiconductor) 4. 74 LS 293 A (Motorola) 5. 74 LS 293 A (Texas Instruments) * * * Download Here; PersianGig http://wdl.persiangig.com/pages/download/?dl=http://betaman.persiangig.com/TTL%20CMOS%20Digital%2074LS%20ICs.zip