The Message

USE ANY COMPUTER LANGUAGE to write the message "this is page 1" on page one, the message "this is page 2" on page 2, and so on until the message "this is page 7" is written to page 7.  Center the messages on the pages, in exactly the same place.  Have the program then alternate the messages and determine if you can detect the fact that each message is rewritten.  Have the program terminate and return to DOS when the q key is pressed.

Amplification:  The words "this is page 1, 2, ...7 is written on the pages as numbering is in a book.  Instead of just listing the page number, the phrase "this is page 1, 2,...7 must be written on each page.