The DeskStation system looks like many PC clones because it is based on an AT motherboard. The basic difference is the additional logic required for the R4000 bus to communicate with the EISA bus. The memory bus is only 32 bits wide, while the CPU itself has a 64-bit-wide path; therefore 512K of secondary cache is used to enhance performance. However, the cache structure was implemented like on the PC-AT, so to the R4000PC there was no secondary cache. The use of relatively slow cache memory, couple with the ill-matched PC-AT style memory architecture caused the 100MHz machine to feel more like a 486-DX33.
For a short time rPC44 support was being worked on and it eventually worked for one person in 1996. However, the perception was that it never reached any functional state, and any functional state that it had in Linux 1.1 was decayed. The rPC44 code has therefore been removed from Linux. At this point, only one DeskStation rPC44 is known to have survived, so support likely will never be restored.
PC Magazine Dec 7, 1993 v12 n21 p39(1) DeskStation's MIPS-based system targets NT work. (DeskStation Evolution Series rPC/44 microcomputer)