The Willem EPROM Programmer is an open-hardware design ROM burner used for socketing and burning custom ECU maps. Because it is an open-design board, it is sold under various names (e.g., "Enhanced Willem," "Dual Powered Willem") and manufactured by multiple vendors.

While cost-effective and capable of burning standard Honda ROM chips like the 27C256 (OTP), 29C256 (EEPROM), and SST 27SF256 / 27SF512 (flash), the programmer relies on a legacy parallel (LPT) port and requires specific configuration.

Warning

Parallel Port (LPT) and OS Requirements: The Willem programmer requires a true hardware parallel port (standard base address 0x378h or 0x278h) to communicate with the PC. USB-to-Parallel printer adapter cables do not work because they do not support direct I/O port mapping. You must use a motherboard with an onboard LPT header or a dedicated PCI/PCI-e parallel card, and a compatible Windows OS (often requiring 32-bit versions or legacy port drivers like UserPort or io.dll to permit direct hardware access).

Programming SST 27SF512 Chips (512k Flash)#

The SST 27SF512 is a 512kbit (64 Kilobyte) flash memory chip. Because it is twice the size of a standard OBD0/OBD1 Honda ROM (32KB), you must configure the software to write the bin file to the upper half of the chip using a hardware or software offset.

Step-by-Step Procedure#

1. Connect and Initialize: Connect the parallel cable and power source (USB or DC adapter). Ensure your parallel port drivers (e.g., DLPortIO) are active.
2. Configure DIP Switches: Set the board's DIP switches according to the software's visual representation for the SST27SF512 device.
3. Insert the Chip: Insert the SST 27SF512 into the ZIF socket. Align the chip so that Pins 14 and 15 are at the bottom slots (closest to the ZIF handle) with the notch facing upward.
4. Erase the Chip: In the software, click the Erase icon.

   Note

   If the erase operation fails, verify that the board's mode jumper is set to the Erase position.

5. Set Jumper for Programming: Swap the board mode jumper from the Erase configuration to the Program/Normal configuration.
6. Apply the 32KB Offset: In the bottom right corner of the Willem software, locate the Offset (Hex) input field. Change the value from 0 to 8000 (32,768 bytes). This shifts the data to the upper 32KB of the chip.
7. Load and Burn: Load your .bin file. Click the Program icon. When prompted to use the specified hex offset, select Yes.
8. Verify: The software will burn the data and automatically run a verification pass. Ensure both operations complete with a 100% status.
9. Final Verification: Insert the chip into your ECU. Turn the ignition to the RUN position. The main relay should click and the Check Engine Light (CEL) should turn off after 2 seconds.

Hardware Configuration#

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Programming SST 27SF256 Chips (256k Flash)#

The SST 27SF256 is a native 256kbit (32 Kilobyte) chip, matching the standard Honda ROM size. No software offsets are required, but the board configuration jumpers must be adjusted.

Erasing the SST 27SF256#

The SST 27SF256 is electrically erasable. Specific jumpers must be repositioned to permit the high erase voltage to route correctly.

Willem Board Jumper Configuration for Erasing SST 27SF256

Burning the SST 27SF256#

To burn the SST 27SF256, return the jumpers to the PCB3 burn position.

Willem Board Jumper Configuration for Burning SST 27SF256