DosQSysInfo

#define INCL_DOSFILEMGR

USHORT  rc = DosQSysInfo(Index, DataBuf, DataBufLen);

USHORT           Index;         /* Which variable */
PBYTE            DataBuf;       /* System information (returned) */
USHORT           DataBufLen;    /* Data buffer size */

USHORT           rc;            /* return code */