Do Unisys latest mainframe systems still use ones' complement representations?

Question

From the Wikipedia article it seems ones' complement representation for signed integers is mostly obsolete, but they mention some Unisys systems, namely the UNIVAC 1100/2200 series as still supporting this representation.

Do the latest systems in the Unisys Clearpath series still support and use ones' complement?

Since they use intel chips, do they require an emulator? How performant is this?

Are there C compilers targeting this architecture?

Answer 1

Yes, the 2200 line still uses ones complement. Emulating one's complement on a two's complement machine is not hard, you just need to add the carry back in (end around carry). And the MCP line still uses signed magnitude.