@PythonLinks AMEM is a 1kx32 bit memory that is partially mirrored in MMEM which is 32x32. They are used more or less as registers, where each address has some purpose. https://tumbleweed.nu/r/sys/file?ci=tip&name=ucadr/uc-parameters.lisp.230&ln=373-557 and https://tumbleweed.nu/r/sys/file?ci=tip&name=ucadr/uc-parameters.lisp.230&ln=559-1269 might give you an idea.