Project 1
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2003-05-04 01:19

Project 1 - Decoding Records

DAT 2343 - Summer 2000

This project is Web-based.  You can do it at school or at home.  The data file comes from the Web, and your decoded answers must be submitted via the Web.

You must be registered with me using my Web Registration form before you can begin this project.


This project starts with a web form, available below.  You must identify who you are by entering the following three things into the Project web form:

  1. Algonquin Userid: This is your 8-character Algonquin EMail userid.  It looks similar to abcd0000 and is made up of the first four letters of your last name and some digits assigned by the College.
  2. Student Number:  This is your 9-digit Algonquin Student number.
  3. Web Password: This is the Web Password you gave me when you used my Web Registration form to register with me at the start of term.  If you haven't yet registered with me using my Web Registration form, do that first.  If you forgot your password, re-register and choose a new one.

After you have identified yourself, you may select one of two buttons on the Web form, corresponding to the two steps you should follow.  The hyperlinks in each of the steps below lead you to the Web form:

Step 1: Create, Download, and Decode:

  1. On the Web form, select 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 on the Web form 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.

Note: The project data file is a binary format file.  It is not printable or viewable on your screen.  It will look like garbage in any text editor you might use.

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, e.g. -123, 123.456, etc.

Step 2: Upload your decoded Answers

After you have decoded all the fields in the data file, return to the Web form again to upload your answers.   Identify yourself and then use the Upload My Answers button on the web form to enter and upload your answers for marking.


As with all questions and comments on course content, please post any problems to the course discussion news group.


Web Author: Ian! D. Allen      Updated: 2003-05-04 01:19

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