Monero hard forked to version 12 of its protocol yesterday. But not everyone is on board. Following the example once set by Ethereum Classic, some users are continuing on the pre-hard fork Monero blockchain… though in this case not as a single project. Now there is Monero Classic, Monero 0 (XMZ), Monero Original (XMO) and a second project by the name Monero Classic (XMC) (which in this article we will refer to as Monero-Classic); these are all continuing on version 11 of the Monero protocol. Of course, this means they are all still compatible on a single network, using the same asset (coin) — just with different names.
The latest hard fork also introduced a tweak to Monero’s CryptoNight proof-of-work hashing algorithm. This backwards-incompatible change makes all existing ASIC (application-specific integrated circuit) mining hardware useless. Such specialized hardware is a bigger concern on the CryptoNight hashing algorithm than most other hashing algorithms, as it could let ASIC miners launch denial-of-service (DoS) attacks on non-ASIC miners and non-mining nodes on the network.