Official .bin files are not directly distributed by HP, but you can extract them from official executable installers.
Processor Support: Includes microcode updates for Intel Core 2 Duo and Quad-core processors to resolve initialization errors like "1801-Microcode Update Error". hp compaq dc7900 bios bin file link
(Automatically: related search suggestions will be prepared.) Official
Note to the reader: Always verify the chip voltage (3.3V for the dc7900). Using a 5V programmer without level shifters will instantly destroy the BIOS chip. You have been warned. Download SPXXXXX
SPXXXXX.exe (e.g., SP54558.exe for v2.32)..bin file (e.g., 786F1_0232.bin).Extract the contents using a tool like 7-Zip. Right-click the .exe file and select "Extract files...".