Project 1 - Decoding Records
DAT 2343 - Fall 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
- 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.
- Student Number: This is your 9-digit Algonquin Student number.
- 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
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:
- 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.)
- 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.)
- 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 an unprintable, 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 in each record:
- one field of 6 EBCDIC-encoded characters
- one 32-bit 2's complement field
- one 32-bit IEEE 754 normalized floating point field
- one 3 byte packed decimal field
- 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
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
My Answers button on the web form to enter and upload your answers for
As with all questions and comments on course content, please post any
problems to the course discussion news group.