Lecture Notes on Memory Map and Address Space Allocation

Introduction to Memory Map

• Memory Map Definition: How the address space is dedicated to various memory chips.
• Decoding Circuits: Use of decoders, AND, and OR gates to decode specific chips.
• Reverse Engineering Task: Previous lecture tasked with identifying address ranges and chip selects for memory boxes.

Address Space Allocation Process

• Smallest Possible Box: Start with the smallest box, e.g., 128 words.
• Address Lines: Requires 7 lines (A0 to A6) for addressing 128 words.
• Table Drawing: Allocate chip spaces in a table format.
• Example: Allocate RAM 1 (128 words), RAM 2 (256 words), etc.
• Address Range Calculation: Convert binary to hexadecimal for starting and ending addresses.

Chip Select Signals

• Example of Chip Select: Chip select for RAM 1 depends on A9, A8, A7 being 0.
• Decoding Logic: Use AND gates for decoding chip select signals.
• Complex Chip Select: Discussed scenarios with multiple rows and different signals.

Address Line Considerations

• RAM 1 vs RAM 2: Different address lines based on memory size.
• Address Line Adjustment: Modify address lines to ensure correct mapping.

Memory Allocation Examples

• Orderly Allocation: Importance of maintaining order through table mapping.
• Generic Method: Use table mapping for generic address space issues.

External Storage Systems

Data Storage

• Tape Drives: Sequential access, large storage potential but slow.
• Hard Disks: Rotating disks, high-density storage, tracks, and sectors.
• Storage Calculations: Example calculation of storage capabilities and rotational latency.

Tape Drives and Disks

• Magnetic Tape Drives: Tape coated with magnetic material, used for massive data archiving.
• Magnetic Hard Disks: Set of rotating disks with read/write heads for data access.
• Sector Reading: Importance of reading complete sectors due to access overhead.

Storage Capacity Calculation

• Example Calculation: 5 GB storage example, calculation of bytes per sector, number of sectors, etc.
• Seek Time and Latency: Calculation of average seek time and rotational latency.

Associative Memory (CAM)

Introduction to CAM

• CAM Definition: Content addressable memory allows data search by content rather than address.
• Parallel Searching: CAM can perform parallel searches, beneficial for cache memory.

CAM Operation

• Example: Bitmap example demonstrating parallel matching.
• Cost and Benefit: CAM is costly in terms of infrastructure but offers fast data retrieval.
• Use in Cache Memory: CAM's fast retrieval makes it ideal for use in cache systems to reduce latency.

Conclusion

• Memory Mapping Techniques: Understanding memory allocation and address maps is crucial for efficient data storage.
• Future Topics: Continue exploring memory systems and their optimization in future sessions.