2 cissp ® Official Study Guide Eighth Edition

Be able to explain the differences between multitasking, multithreading, multiprocessing, 
and multiprogramming.
Multitasking is the simultaneous execution of more than one 
application on a computer and is managed by the operating system. Multithreading permits 
multiple concurrent tasks to be performed within a single process. Multiprocessing is the 
use of more than one processor to increase computing power. Multiprogramming is similar 
to multitasking but takes place on mainframe systems and requires specific programming.
Understand the differences between single-state processors and multistate processors.
Single-state processors are capable of operating at only one security level at a time, whereas 
multistate processors can simultaneously operate at multiple security levels.
Describe the four security modes approved by the federal government for processing
classified information.
Dedicated systems require that all users have appropriate clear-
ance, access permissions, and need to know for all information stored on the system. 
System high mode removes the need-to-know requirement. Compartmented mode removes 
the need-to-know requirement and the access permission requirement. Multilevel mode 
removes all three requirements.
Explain the two layered operating modes used by most modern processors.
User applica-
tions operate in a limited instruction set environment known as user mode. The operating 
system performs controlled operations in privileged mode, also known as system mode, 
kernel mode, and supervisory mode.
Describe the different types of memory used by a computer.
ROM is nonvolatile and 
can’t be written to by the end user. The end user can write data to PROM chips only once. 
EPROM/UVEPROM chips may be erased through the use of ultraviolet light and then can 
have new data written to them. EEPROM chips may be erased with electrical current and 
then have new data written to them. RAM chips are volatile and lose their contents when 
the computer is powered off.

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