Windows 98 build 2120

Windows 98 build 2120 is a beta build of Windows 98 Service Pack 1, which was first shown in a BetaArchive topic by DiskingRound on 23 December 2015 and was later shared by the aforementioned user one month later on 24 January 2016. It should not be confused with Windows 98 SE build 2120, which was planned as a OEM Service Release and eventually resulted in the Windows 98 Second Edition.

Installation
The self-extracting archive  starts the update installer   with -q and -z arguments, which means silent install, no automatic restart. Just wait a while for disk activity to stop, then restart the machine to finish the installation.

Alternatively, you can unpack the archive and run  yourself to get the usual installer UI.