Does anybody knows how can I use my old antminer s7 to mine alt coins like monero, zcash …?
different coins use different mining algorithms. For example – Bitcoin uses SHA-256. Monero and Zcash use different algorithms and therefor your ASIC miner (i.e. Antminer S7) isn’t compatible with them. I’m not sure whether you can still mine with it, but I am sure that it won’t be very efficient. Here’s a guide about Monero, there’s also a section about CPU mining.