> What I generally wonder is, why ISAs don't have special instructions for a task that is so common. ISAs used to have instructions to support binary coded dec

> What I generally wonder is, why ISAs don't have special instructions for a task that is so common. ISAs used to have instructions to support binary coded decimals (BCD). BCD encoding stores values as 0x[0-9][0-9], and the instructions provide math operations on that representation. On x86, these still exist, for example AAD: https://c9x.me/x86/html/file_module_x86_id_2.html https://c9x.me/x86/html/file_module_x86_id_2.html Other ISAs (eg 6502) had a processor flag to switch between regular and BCD mode.