`Vgmn`::
 * functionality : a generic VCI compliant micro-network
 * Mandatory arguments:
   * `instance name`
 * Optional arguments:
   * `min_latency`
 * Example:
{{{
my_vgmn = Vgmn("my_vgmn", 10)
}}}

 `Xcache`::
 * functionality: a direct mapping cache controler (separated instruction & data cache)
 * Mandatory arguments:
   * `instance name`
 * Optional arguments:
   * `dcache_lines` : number of lines in data cache
   * `dcache_words` : number of words per line in data cache
   * `icache_lines` : number of lines in instruction cache
   * `icache_words` : number of words per line in instruction cache
 * Example:
{{{
my_cache = Xcache("my_cache", dcache_lines = 32, dcache_words = 8, icache_lines = 32, icache_words = 8)
}}}

 `Mips`::
 * Functionality : a MIPS R3000 micro-processor
 * Mandatory arguments:
     * `name`
 * Example:
{{{
my_proc = Mips("my_proc")
}}}

 `MultiRam`::
 * Mandatory arguments:
   * `name`
 * Optional arguments:
   * a list of segments, allocated with Segment()
 * Example:
{{{
my_ram = MultiRam("my_ram", seg1, seg2, seg3)
}}}

 `MultiTty`::
 * functionality: a TTY controler (up to  256 TTYs)
 * Mandatory arguments:
   * `instance name`
   * an ordered  list ot names (one name per emulated terminal) 
 * Example:
{{{
my_tty = MultiTty("my_tty_controler, "TTY0", "TTY1", "TT2")
}}}