Definition
An EEPROM (Electrically Erasable Programmable Read-Only Memory) is the small non-volatile memory chip found on each Antminer hashboard that stores the board's identity and per-board calibration data. When the control board boots and initialises a hashboard, it reads this EEPROM first. The data it finds, board serial number, chip configuration, voltage trim values, and frequency tables, tells the firmware how to drive that specific board safely.
Why per-board calibration exists
No two hashboards are electrically identical. During factory testing, each board is characterised and its optimal voltage and frequency parameters are written to its EEPROM. This lets the same firmware run boards that vary slightly in silicon quality without the user tuning anything. On some models a PIC microcontroller (such as the PIC16F1542 on conventional S19j Pro boards) holds this data in its internal EEPROM instead of a discrete chip; "noPIC" variants move the function elsewhere.
What goes wrong
If the EEPROM data is corrupted, the board can behave erratically or refuse to initialise even when every chip is physically healthy, often surfacing as an EEPROM error in the kernel log. Repairs may involve reading a known-good dump and reprogramming the chip with a hashboard code editor. Because the data is board-specific, blindly flashing the wrong dump can mis-tune a board.
The EEPROM is read during the same boot sequence that populates the diagnostic output. See Kernel Log for where EEPROM errors are reported, and Test Fixture for the bench tool used to verify a board after reprogramming.
In Simple Terms
An EEPROM (Electrically Erasable Programmable Read-Only Memory) is the small non-volatile memory chip found on each Antminer hashboard that stores the board’s identity and per-board…