testrom

Test ROM, sometimes written as test ROM or testrom, refers to a read-only memory containing diagnostic routines and self-testing code used to validate hardware components at power-up or during manufacturing. It is common in embedded systems, microcontrollers, and system-on-chip designs, where a dedicated test ROM may be present alongside regular firmware to facilitate debugging and production tests.

The contents typically include memory integrity tests (such as walking ones and walking zeros), CPU instruction and timing checks, peripheral and I/O tests, clock calibration, and basic system diagnostics. Some designs store test sequences that exercise buses, memory interfaces, and interrupt handling to verify correct operation before normal software starts. Output mechanisms for test results may include LEDs, a serial port, or a diagnostic interface, depending on the hardware.

Usage and lifecycle: On power-up, the system may boot into the test ROM or into a test bootstrap that runs the test routine and then reports results. In development, test ROMs are used with hardware test rigs to check boards during assembly and debugging; in production, dedicated test firmware may replace or supplement normal firmware to perform automated checks.

Purpose and access: Because test ROM is often intended for development or manufacturing, it is typically isolated from end-user operation and may be disabled or overwritten after testing. Its design emphasizes reliability and reproducibility rather than feature functionality. See also power-on self-test, boot ROM, and diagnostic firmware.