It is frequently non-flashable (locked), meaning once you have it, you cannot easily upgrade or downgrade the firmware without an external programmer (e.g., TL866). 2. Top Sources & Downloads (As of 2026) A. Best Places to Buy/Download AliExpress
Searching for "OPCOM V1.99 PIC18F458" often leads to listings that include the required software and drivers. Internet Archive opcom firmware 199 hex file top