Field-programmable

An electronic device or embedded system is said to be field-programmable or in-place programmable if its firmware (stored in non-volatile memory, such as ROM) can be modified "in the field," without disassembling the device or returning it to its manufacturer.

This is often an extremely desirable feature, as it can reduce the cost and turnaround time for replacement of buggy or obsolete firmware. For example, a digital camera vendor could distribute firmware supporting a new image file format by instructing consumers to download a new firmware image to the camera via a USB cable.

When a device's firmware is stored in mask ROM or one-time programmable PROM, it cannot be modified without physically replacing the integrated circuit, so such a device cannot be field-programmable in the modern sense. EPROM-based firmware can be erased and reprogrammed, but only after lengthy exposure to a high-intensity ultraviolet light source.

Thus, field-programmable devices were not practical until the invention of EEPROM and flash memory in the 1980s. Early EEPROMs could only be reprogrammed with expensive, dedicated programmer hardware, since they required high voltages (10-20 V, compared to typical 3-5 V logic levels) and there was no standard programming ; as a result, field-programming was mostly performed by professional technicians and service engineers. However, as of the early 2000s, many devices were expressly designed to be field-programmed by ordinary consumers. Several developments have made this possible:

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