An Organizer is a flat computer interface that can be input any information and can interface with other computer systems. Dot Matrix uses hers to keep track of all her business information as well as important information about Mainframe itself. It is password protected so that Dot is the only allowed to use it. After meeting Bob, Dot made the password "Guardian", but she revieled that password to Captain Capacitor, so it's probable that it has been changed since that time.
Dot has been seen using her organizer since she was a teenager. She used it during the construction of Dot's Diner to keep track of the construction schedule and all the materials going into the building. She also had a clock on it to tell her when it was time to go to her father's presentation. Dot got so absorbed in the construction that she was very late for the presentation, this saved her and her brother, Enzo from the destruction of Mainframe's Twin City. (Daemon Rising)
Dot used her organizer to collect the PID's of the inhabitants of a sub-sector of Giedi Prime under Megabyte's control. The file was removed by Cyrus and delivered to Megabyte for infection. After a short time Dot figured out a way to get it back by hacking into Megabyte's system and using her password to access the file and re-download it. The file was uploaded to the Principal Office where Phong registered them online and the sector was converted into an Energy Park. (Identity Crisis, Part 1)(Identity Crisis, Part 2)
Megabyte invaded the Principal Office and took control of the Core Control Chamber. Bob and Dot were trying to find weapons when Megabyte released game pucks from Phong's favorite game Pong. They are energy seaking and loaded with electromagnetic detonators. Bob's Key Tool, Glitch, had no more power and Bob asked Dot if her organizer had a jumper cable on it. He used it to transfer the power from the organizer to Glitch and saved him and Dot from the oncoming game pucks. (Infected)