1. 1 Chapter Overview ROM and RAM Memory Mapping

2. 2 Defining Memory Memory is the area within a computer where information is stored while being worked on. Information is stored by using 0s and 1s as switches. When strung together, these switches can represent large numbers and code values.

3. 3 Nonvolatile and Volatile Memory Computer memory includes two major classes. Nonvolatile: computer retains data when the power is shut off Volatile: computer loses data when the power is shut off

4. 4 Read-Only Memory (ROM) Is nonvolatile memory, generally installed during manufacturing Protects the information required to start and run the computer Holds instructions for performing the power- on self test (POST) and basic input/output system (BIOS) information Requires attention only if it needs to be replaced or upgraded

5. 5 Random Access Memory (RAM) Is volatile memory Includes two common forms Dynamic RAM (DRAM) Synchronous DRAM (SDRAM) Uses two methods to ensure data integrity Parity Error-correction encoding (ECC)

6. 6 RAM Packaging

7. 7 Memory Configuration 8-bit data bus requires memory in 8-bit chunks. 16-bit data bus requires memory in 16-bit chunks. 32-bit data bus requires memory in 32-bit chunks.

8. 8 Installing SIMMs Check the memory module voltage. Use electrostatic discharge (ESD) protection and handle single inline memory modules (SIMMs) carefully. Insert the SIMM at a 45-degree angle and click it into place. (The notch in the SIMM prevents improper installation.)

9. 9 Cache Memory

10. 10 Hexadecimal Code

11. 11 Memory Allocation

12. 12 Shadow RAM

13. 13 Determining Usable Memory MEM.COM Display

14. 14 Chapter Summary The two basic computer memory types are ROM (nonvolatile) and RAM (volatile). RAM is packaged in a variety of designs. Installing SIMMs requires ESD protection and careful handling. Cache memory enhances performance. Hexadecimal code simplifies binary code notation. Memory allocation has been simplified under Microsoft Windows.