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.