The Passport 4400 utilizes a 16 megabyte nonvolatile Flash SIMM to store the operating software. The two types of data stored include: boot code (loader program, power-on self tests, diagnostics and other start-up information), and application code (operating system modules for the user services).
An additional 128 kilobytes of non-volatile memory in the Passport 4400 stores the configuration data, which consists of factory default parameter values plus those parameter values set or changed by the user.
All non-volatile memory is logically divided into five memory banks, as follows:
| Bank 0 | Boot code |
| Bank 1 | Application code |
| Bank 2 | Application code |
| Bank 3 | Configuration data |
| Bank 4 | Configuration data |
The above makes it possible for the Passport 4400 to store two different versions of application code and two different versions of configuration data. (Only one version of boot code can be stored in Bank 0.)
This section discusses the following:
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