Hello @Mark Scott Welcome to Microsoft Q&A Platform!,
I hope the below information helps with your initial query.
MT3620 has 16MB of flash and 4 MB of RAM total.
- For high-level apps
1MB Flash for customer app binary
64kb Flash for mutable storage that the customer app can write/read (e.g. to permanently save data across reboots)
256KB of user RAM for the customer app
- For RT apps
192kb per core to store application binary
64kb of ram per core
RT apps can't use flash
There are 2 RT cores, hence customers can use twice the above for RT Core
The rest of the flash and RAM is used for OS and not available for customer applications.
You may have already referred to this document: Memory available on Azure Sphere
Please let us know by commenting below if you need further help/clarification in this regard.