Where in the ECU are the data saved?
Data from Chip Tuning are stored in microchips - of which there are different types:
An EPROM is a non-volatile, electronic memory chip that has a long history of use in microelectronics. EPROMS have the characteristic of being able to be reused after their data has been erased. With the help of specialized instruments EPROM data is programmed, erased by UV rays and then reprogrammed with new data. The first electronic ECUs contained non-erasable PROMS. After 100-200 erasures, an EPROM is usually in need of replacement. The quartz window inside of the EPROM case is quite expensive and though there are designs without windows a.k.a. OTPs, they can only be programmed once.
An advancement on the design of the EPROM, the EEPROM (Electrically Erasable PROM or E2PROM), is an electronically erasable chip with the ability to erase individually even the smallest memory units. In contrast to the “standard” EEPROM, Flash EPROMS cannot individually delete bytes. EEPROMS and Flash EPROMS are erased through electrical tension. These chips are used in a variety of applications where information must be stored and is continuously being exchanged (non-volatile) in the smallest of spaces and without a continuous supply of electricity. In the case of ECUs where information must be retained after a drop in voltage or expansion of their data, these chips are the key to increases in engine performance.