Project 1
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2003-09-23 11:45

Project 1 - Decoding Records

DAT 2343 - Winter 2000

This project is Web-based.  The data file comes from the Web, and your answers must be submitted via the Web.  There are two buttons on the Web form, corresponding to the two steps you should follow

You are asked to enter your full name.  Make sure you use the same name for both steps in the project!

Step 1: Create, Download, and Decode:

  1. Enter your name and use the Create Project File button to create your own personal Project 1 data file.  (Each person will have a different file.)
  2. Follow the directions to save the data file on your local computer.  Make sure that the file is of the correct size on your computer.  (See the next point.)
  3. Use a file dump utility (e.g. DOS DEBUG or the Linux "od" command) to display the hexadecimal byte contents of your personal data file.  Using your knowledge of data encoding, decode the four 22-byte records in this file into plain ASCII and decimal numbers.

Record and File Format

Each record in your personal data file has the same structure.  There are five fields per record:

  1. one field of 6 EBCDIC-encoded characters
  2. one 32-bit 2's complement field
  3. one 32-bit IEEE 754 normalized floating point field
  4. one 3 byte packed decimal field
  5. one 5 byte zoned decimal field

Adding up the above sizes, you see that each record is 22 bytes long. There are four records in your data file, giving a total file size of 88 bytes.  (Make sure your downloaded data file is exactly this big, before you begin!)

As implied by the EBCDIC fields, this is an IBM mainframe simulated file; as a result, the 2's complement and the floating point fields are not in the reverse byte order you would expect for a standard MS-DOS ASCII dump. The byte order you see is the byte order you decode.

Decode the file into four records with five fields each. Decode the first field of each record into characters; decode the other four numeric fields into ordinary decimal numbers.

Step 2: Upload your decoded Answers

After you have decoded the file, enter your name again and use the Upload My Answers button to enter and upload your answers for marking.

To upload your answers, use exactly the same name you entered in Step 1.


If there are any problems with the Web interface (this is the first term I've used it), please let me know immediately!


Web Author: Ian! D. Allen      Updated: 2003-09-23 11:45

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