Unveiling the Hidden Secrets of a 1970s Mask ROM MCU
A clever hack has been discovered to dump the contents of a Mostek MK3870 chip, a 1970s mask ROM microcontroller. By utilizing the TEST pin to disable the mask ROM and load alternative program code directly into the micro's processing core, the ROM's contents can be read out. Although implementing the hack had strict timing requirements, the code can be optimized for dumping multiple chips. Mask ROMs are known for their long-term data storage capabilities.