History
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. Erasable PROM-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 protocol; 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: * Modern EEPROM and flash devices contain internal charge pumps which eliminate the need for high voltages. * Most consumers have access toProgrammable logic
The 1980s saw the introduction of programmable logic devices (PLDs) such as PALs, PLAs, and CPLDs. These are integrated circuits which can implement nearly arbitraryHobbyist opportunities
Many consumer electronic devices (includingSee also
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