Most Altcoins inherit the Bitcoin framework: publishing,coin control,transaction,confirmation.

As to make difference from Bitcoin, an Altcoin will change these following parameters:

Block reward and half life 

POW algorism 

Difficulty algorithm

address header

packet magic

transaction fee

communication port.

As an offline wallet, it doesnt need to care about mining parameters. Only 3 parameters are involved: address header, packet magic, transaction fee.

So,by using the corresponding 3 parameters for each coin type,the system can handle all the transactions in each coin type.

In more details, the construction of an cryptocurrency address has 3 parts:

Address header (1byte) public key hash160(20bytes)  Checksum (4bytes)

The shown address string is a base58 encoding of the address bytes.

By changing the address header, the base58 encoded address string will looks totally different.But actually the main part-public key hash160 is exactly the same.

 

The basis of Hardbit Hardware wallet is explained in Technical White Paper of Hardbit—a Bitcoin Hardware Wallet