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