• [How-To] Force 2/2/2010 OTA Update - Android Forums
  The procedure: 1. obtain the update.zip file 2. reboot into the bootloader 3. select recovery 4. apply sdcard:update.zip Specifics Obtain the file
  in Nexus one > Updates HOW TO with bootloader file nexus obtain procedure reboot update.zip updates
• XDADeveloperWiki - SPL Questions?
  The SPL is mainly a bootloader which allows a ROM to be flashed onto your device. As has been uncovered recently (or known to the more astute longer) the SPL does more than just load and boot the ROM it sets various flags which can control the operation of the OS on the device. It also controls some operations between the OS and the device's hardware. SPLs come paired with shipped (or leaked) official ROMs and are meant to match the ROMs operation. Therefore, with each new ROM release there is likely to be a new SPL. As you read on you will learn more about the SPL...
  in Nexus one > Rooting the Phone with bootloader flashed mainly nexus phone rom rooting spl

bootloader from all users