1. Von Neumann model - Memory
Memory is an array of Cells.
Memory keeps information in the cells.
Each Cell has a unique address and could be selected by its Address.
Information could be loaded from Memory Cell to Register or stored from Register to Memory Cell.
The source of information in this case is not changed. Only the destination is overwritten.

2. Memory example 4 cells In this example: The memory contains 4 Cells.
They are addressed by 2 bit address which is enough to select all 4 Cells.
If the memory is larger, then the address bits have to be more to be able to address more Cells.

3. Memory example 8 cells, 8 bits
Address length is 3 bits
Memory Cell length is 8 bits (1 byte)
We can load or store 8 bits at once.
3 address bits address 23 = 8 Memory Cells.
Data and Address registers lengths do not depend each of other.

4. Memory example 8 cells, 16 bits
Address length is 3 bits
Memory Cell length is 16 bits (2 bytes)
We can load or store 16 bits at once.
3 address bits address 23 = 8 Memory Cells.
Data and Address registers lengths do not depend each of other.

5. Larger Memories. MIPS Memory.
8 bit (1 byte ) memory cells
8 bit
Address Register
0xFF
. . . 28
Bytes
(256) 00 03
0x03
0x03
0x02
0x01
0x00
0x68
General Purpose
Register $2
8 bit Data Register
4 bytes Data Register
6 B
General Purpose Register $5

6. MIPS model 232 cells, each 8 bits
MIPS memory is an array of 232 bytes.
Each byte has a 32-bit address.
Each byte can hold an 8-bit pattern, one of the 256 possible 8-bit patterns.
The addresses of MIPS main memory range from 0x to 0xFFFFFFFF.
232 bytes Memory Size
Operations
Load: a bit pattern starting at a designated address in memory is copied into a register inside the processor.
Store: a bit pattern is copied from a processor register to memory at a designated address.
Address bits
General Purpose Register

7. MIPS memory layout
The lower half (most of it anyway) is for user programs.
User memory is further divided (by software convention) into text, data and stack segments.
Text Segment: This holds the machine language of the user program (called the text).
Data Segment: This holds the data that the program operates on.
Static Data
Dynamic Data
Stack Segment: With high level languages, local variables and parameters are pushed and popped on the stack as procedures are activated and deactivated.
ROM, Device buffers, … not available for user programs
Dynamic Data
Dynamic Data
Static Data
User program machine code
User programs and data are restricted to the last 231 bytes. The last half of the address space is used for specialized purposes.
OS Kernel