File Storage and Access Methods

File Organization and Access Methods

• Sequential files use an index of key fields to locate records, enhancing search efficiency compared to scanning the entire file.
• Random access files employ hashing algorithms that calculate record addresses based on key fields.

Hashing Algorithms

• Hashing algorithms represent mathematical formulas applied to key fields, providing calculated addresses for record retrieval.
• More complex hashing methods are utilized in data encryption.
• A basic hashing example: For 2000 records and key values between 1 and 9999, the address is determined by the remainder of the key divided by 2000.
• Storing a record with a key value of 3024 results in an address of 1024, assuming a start address of 0 and single storage location per record.

Floating-Point Numbers Representation

• Denary numbers can be converted to binary, with examples including conversions of values such as +48 and -100.
• Binary numbers can also be transformed back to denary, with various examples outlined.
• Use of two’s complement allows for finding negative values from binary representations.

Binary Calculations and Representations

• Example binary additions should be shown step-by-step for clarity.
• The exponent in binary can dictate the adjustment of the binary point for proper conversion to denary.
• Negative floating-point numbers also can be converted using two's complement for accurate results.

Methods for Floating-Point Conversion

• Two methods exist for converting binary floating-point numbers to denary:
  • Method 1 involves summing mantissa and exponent values based on bit appearances.
  • Method 2 uses two’s complement for accurate representation before adjusting for the negative value.

Challenge Activity

• Activity to convert binary floating-point numbers into denary, maintaining an 8 bit mantissa and exponent for all examples.

This quiz covers the concepts of sequential and random access files, focusing on the use of indexes and hashing algorithms for efficient data retrieval. Understand the benefits of searching through an index versus a full file scan, especially for large datasets.