... Systems, later XDS after acquisition by Xerox) being similar to the SDS Sigma-7 and Sigma-9 computers. There is a SIMH simulator of the Sigma computers, with an operating system (CP-V) in binary form that works like the original.
This is a simulator of one single threaded Felix job that must consist of a restriction to the most commonly used instructions and of the ASSIRIS assembler, together with essential control instructions and macros.