Operating System (OS)
The Memory Buffer Register (MBR)

is a group of electrical circuits (hardware), that performs the intent of instructions fetched from memory.
None of these
is a hardware memory device which denotes the location of the current instruction being executed.
contains the address of the memory location that is to be read from or stored into.
contains a copy of the designated memory location specified by the MAR after a "read" or the new contents of the memory prior to a "write".

ANSWER DOWNLOAD EXAMIANS APP

Operating System (OS)
Memory management is :

not used in modern operating system
critical for even the simplest operating systems
replaced with virtual memory on current systems
not used on multiprogramming systems
None of these

ANSWER DOWNLOAD EXAMIANS APP