Mobile Operating Systems and Software Basics
Mobile Operating Systems and Software Basics tests how software layers control hardware, store data and fail. The exam expects you to distinguish user-data, firmware and hardware faults before recommending a reset or flash.
Layers and boot flow
Android and iOS both use a kernel, hardware abstraction and drivers, system services and apps. A bootloader verifies and loads the kernel; Android adds recovery and fastboot modes, while iOS uses recovery and DFU modes. Android Debug Bridge (ADB) allows authorised diagnostics; fastboot writes partitions. Apps run in sandboxes with permissions, so a camera app can fail because permission is denied even when the camera module is good. Over-the-air updates replace system images; a failed update can leave a boot loop.
Data, reset and activation locks
A factory reset erases user data and restores default settings but does not repair a damaged PMIC or display. Android Factory Reset Protection and iOS Activation Lock require the previous account credentials after reset. Flashing must match the exact model and firmware; anti-rollback counters can permanently reject older images. A backup should be attempted before any destructive step, and the customer must consent to data loss.
Worked example
A phone boots to the logo then restarts. The technician first backs up if possible, then boots safe mode or recovery. If safe mode is stable, a third-party app is likely; if recovery works but the system does not, a corrupt update or partition is likely; if neither recovery nor fastboot responds, check hardware and bootloader access before flashing.
Traps
Do not flash firmware to cure a charging fault. Do not reset a customer’s phone without consent and a data-loss warning. Do not bypass FRP or Activation Lock; it is an account-owner security control. Verify model number, build number and region before any write.