25. What is the OS name of Multiple Virtual Storage? а) IBM MVS
б) DEC RSX
в) DEC VMS
г) CTSS
д) IBM VM
26. What is file?
а) the named area on the disk
б) part of the disk
в) sequence of operators and commands
г) data processing program
д) none of the above
27. How many levels of computer systems we know?
а) 4
б) 3
в) 5
г) 2
д) 6
