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
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