sx simulator

microcode generator is taken from s2/mgen.
simulator is taken from s2/s2micro.

microprogram notation

The special symbols will appear in the C source file for the simulator, therefore it must conform C language, I use only "_".

for a multiplexor, "_" is used to indicate the selector, "mux_selector".  A label is prefixed with ":" as ":label".  A comment line starts with ".".  A reference to lable in "goto label" is prefixed with "/" as "/label".

In C header, all signals, mux, latch registers, are prefixed with "s_", and all labels are prefixed with "a_".  For example:

x_ts   becomes  s_x_ts
lpc    becomes  s_lpc
:add   becomes  a_add
