A backup ZIP archive with the official Canon firmware update 2.0.0.0 for the SX1 IS is also available from the CHDK Google Drive, section "others":
https://drive.google.com/open?id=0B08pqRtyrObjUDIyZHpPbHhvWEUfilename: SX1is 2.0.0.0 official firmware update.zip
The ZIP file contains the update instructions and the firmware update files as Windows & Mac self-extract executables.
If needed, the firmware files can be extracted easily with common unzip tools, e.g. 7-zip (
www.7-zip.org ) to copy the needed files directly to the memory card.