Honda ECU EPROM Compatibility Reference
A technical reference for EPROM compatibility in OBD0 and OBD1 Honda ECUs, including common chip types and pin-compatibility requirements.
EPROM (Erasable Programmable Read-Only Memory) is a type of non-volatile memory used to store ECU calibration data. These chips are programmed using a dedicated ROM burner.
Compatible EPROM Types
The following chips are commonly used for Honda ECU tuning due to their pin-compatibility with standard OBD0 and OBD1 ECU sockets:
- 27C256: A standard UV-erasable EPROM.
- 29C256: An electrically erasable (EEPROM) alternative, often preferred for its ease of reprogramming.
Important
While the 28C256 is frequently encountered, it is not pin-compatible with standard OBD0/OBD1 Honda ECU sockets and should not be used as a direct replacement.
Technical Specifications
| Chip Model | Type | Erasure Method | Compatibility |
|---|---|---|---|
| 27C256 | EPROM | UV Light | OBD0/OBD1 |
| 29C256 | EEPROM | Electrical | OBD0/OBD1 |
| 28C256 | EEPROM | Electrical | Not Compatible |
Tip
When selecting a chip for ECU tuning, ensure the access time (measured in nanoseconds, e.g., 120ns or 150ns) meets or exceeds the requirements of the ECU's processor to prevent data read errors.
Related Components
- ROM Burner0: Hardware required to write data to the EPROM.
- ECU0: The target engine control unit requiring the programmed chip.