NXP LPC55S6x microcontrollers (0A and 1B), i.MX RT500 (silicon rev B1 and B2), i.MX RT600 (silicon rev A0, B0), LPC55S6x, LPC55S2x, LPC552x (silicon rev 0A, 1B), LPC55S1x, LPC551x (silicon rev 0A) and LPC55S0x, LPC550x (silicon rev 0A) include an undocumented ROM patch peripheral that allows unsigned, non-persistent modification of the internal ROM.