The above logisim model comes under the domain of Digital Devices. The objecive of the above model is to act as a initial login system where user enters a four 7-bit ASCII key to enter into a particular file system and its validity will be verified  by the model based on the ASCII value entered by the administrator. It is easy any compatible compare to any simple Analog Devices.  The important functionalities involved in the model: 1. Admimisitrator is provided with a ENABLE button to set the initial password key. 2. User is provided with a ENTER_VALUE, CLEAR_KEYBOARD and ATTEMPT buttons and a variable clock to set the simulation. 3. Every user can make an continuos attempt of 3 times. 4. After 3 attempts, the entire model will block for a time period of 9 seconds. 5. When a User enters a valid ASCII value it shows an output in the component TTY and the User can proceed with the further file systems.  Technologies Used: Logisim.