This information is from defind.c, version 3, of 3 June 1991.

The following tokens are predefined by the preprocessor/compiler for
386 PC, MS-DOS, Microsoft C 6.00:
                 M_I8086 (1)
                   M_I86 (1)
                 M_I86SM (1)
                _MSC_VER (600)
                   MSDOS (1)
           __TIMESTAMP__ (Tue Jun 04 12:19:13 1991)

Additionally, the following standard tokens are defined:
                __FILE__ (defind.c)
                __LINE__ (5506)
                __DATE__ (Jun 04 1991)
                __TIME__ (12:20:06)
