This thesis proposes an efficient parameter access scheme on the microarchitecture level for microprogram languages, which is called the "Indexed Parameter Access Scheme". This thesis also presents the development of the scheme within a microarchitecture that emulates the IBM system/370 architecture and evaluates the scheme in the view of vertical migration and microprogrammability. As the result, advantages of the scheme are: ease of vertical migration, ease of microcode generation, reduction of overall execution time and control store space, and saving of hardware resources.