INT 60 u - HP 95LX System Manager - READ FROM FILE
        DI = 0504h
        STACK:  2 WORDs unused dummies (for calls from high level languages)
                DWORD   pointer to file state record (see INT 60/DI=0500h)
                DWORD   pointer to data buffer
                WORD    number of bytes to read
                DWORD   pointer to WORD in which to return actual bytes read
Return: ???
        STACK unchanged
SeeAlso: INT 60/DI=0505h