020-5420 is a microcontroller from Elma, a company that specializes in microelectronics. It is part of their BLM Series of 8-bit microcontrollers. It features 8kbytes of Flash Memory, plus 128 bytes of RAM and 1024 bytes of EEPROM memory. It has an 8-channel 10-bit A/D converter, and two 8-bit timers. It also has 2 serial interfaces, with 9 I/O lines and 5 interrupt sources.