- Review: Computer memory
- Computer memory consists of
memory cells (= bytes)
that are identified by
a unique address
- Computer memory consists of
memory cells (= bytes)
that are identified by
a unique address
- Important fact:
- Each
memory cell can be
marked as
- unused (or available (for use)) or
- used (i.e., reserved for a certain purpose)
-
The memory cells are
marked by
the memory manager process
in the Operating System
- How the
memory manager does this is
beyond the scope of
this course.
Take CS450 (Systems Programming) to learn more about this.
- How the
memory manager does this is
beyond the scope of
this course.
- Each
memory cell can be
marked as
- Initially, the
entire memory is
unused:
When a program is loaded into the memory for execution, a part of the memory is marked as used:
- Very important fact:
-
The memory manager
must
keep track of
which memory cells have been
used
(and unused), because:
- Otherwise, the computer system may re-used the same memory cell to store something else !!!
This will destroy some important value stored at used memory cell !!!
-
The memory manager
must
keep track of
which memory cells have been
used
(and unused), because:
- Initially, the
entire memory is
unused:
- When a program is
loaded for execution,
the memory is
organized as
follows:
The top part of the computer memory contains:
- The (computer) instructions
that execute the
statements in the
computer program
- The class variables !!!
Recall:
- Class variables
exists for the
entire execution
of the computer program
(You can see now that the class variables are created when the program is loaded into the computer (RAM) memory)
- Class variables
exists for the
entire execution
of the computer program
- The (computer) instructions
that execute the
statements in the
computer program