Which software version can be installed on the RB133 RouterBoard?

The correct choice for the RB133 RouterBoard, which is based on a MIPS little-endian architecture, is the software version designed specifically for such platforms: routeros-mipsle-x.xx.npk. The "mipsle" in the file name indicates that it is intended for MIPS little-endian architecture, which is compatible with the hardware of the RB133.

When selecting the appropriate software version for a MikroTik RouterBoard, it is crucial to align the architecture specified (such as MIPS little-endian) with the capabilities of the RouterBoard itself. Each RouterBoard model is designed for specific types of software, and using an incorrect version can lead to operational failures or functionalities being unavailable.

The other options, while similar, do not match the architecture required by the RB133. For example, "mipsbe" refers to MIPS big-endian, which is not compatible with the RB133. Therefore, only the version that corresponds to MIPS little-endian will successfully run on the RB133 hardware, making it the correct choice.