The history of 64-bit programs is not new and makes more than a decade already [1]. In 1991 the first 64-bit microprocessor MIPS R4000 was released [2, 3]. Since that time the discussions devoted to porting the programs to 64-bit systems appeared in forums and articles. There began a discussion of the problems connected with the 64-bit programs development in C language. There were discussed the following questions: which data model is better, what is long long and many others. Here, for example, is an interesting collection of messages [4] from comp.lang.c news group devoted to using long long type in C language, which, in its turn, was connected with 64-bit systems appearance.

One of the most wide spread and sensitive to the change of the digit capacity of data type is C language. Because of its low-level features, it is necessary to constantly control the correctness of the program ported to a new system in this language. It is natural that with the appearance of 64-bit systems the developers all around the world again faced the problems of providing the compatibility of the old source code with the new systems. One of the indirect evidences of the difficulty of program migration is a big number of data models which must be constantly taken into consideration. Data model is a correlation of the size of base types in a programming language.