MEMU is a Memotech MTX/FDX/SDX emulator.
It was written in the hope various bits of historical software can be kept running a little longer on emulated Memotech hardware.
It runs on Linux+XWindows, Windows and MacOSX (beta quality). With a recompile, it'll probably run on other UNIXes+XWindows.
Beyond MEMU, REMEMOTECH is a REimplementation of a MEMOTECH compatible computer, in hardware, and REMEMOrizer is an add-on based upon this technology.