Visit support.hp.com and search for “Samsung ML‑2850 Laser Printer series.” From there you can select your operating system and download the latest drivers and firmware packages.
Once flashed, the printer no longer needs a chip. Firmware Samsung ML 2850 --
That printer was popular for its reliability and low cost per page, but its firmware is interesting for a few reasons: Visit support
For the base ML-2850 (no USB host), you must use a JTAG programmer or send the mainboard to a specialist. Firmware Samsung ML 2850 --
Using non-official firmware will void your manufacturer warranty.