block SysArch
DB db_c;
S1 s1_c;
S2 s2_c;
connect(db_c.input[1], s1_c.output);
connect(db_c.output[1], s1_c.input);
connect(db_c.input[2], s2_c.output);
connect(db_c.output[2], s2_c.input);
end SysArch