Access to an ISDN card from Modula-2

Abstract Methods to access complex memory-mapped peripherals from modula-2 programs are discussed and it is demonstrated that assembly language modules are rarely needed. Efficient solutions, however, require detailed knowledge of the compiler code generation process and of the target hardware structure. Procedures and data structures are presented which access an ISDN card in a Macintosh Nubus-slot. The solutions offer a standard interface to the operating system and meet the stringent realtime conditions of the 64 kbit s−1 ISDN channels. Examples are given for elegant and for less elegant solutions.