I think it is a MIPS VR4121, if so I tried to install linux in my z50 and the available kernels are very old, and lack functionality, please look at: http://www.peanuts.gr.jp/~kei/soft-install.htm
But netbsd have updated kernels and packages for mips vr4121!!!! Installed ok in my z50 ( need at least a 1GB microdrive or more).