* `Vgmn`
   * Mandatory arguments:
     * `name`
   * Optional arguments:
     * `min_latency`

 * `Xcache`
   * Mandatory arguments:
     * `name`
   * Optional arguments:
     * `dcache_lines`
     * `dcache_words`
     * `icache_lines`
     * `icache_words`

 * `Mips`
   * Mandatory arguments:
     * `name`

 * `MultiRam`
   * Mandatory arguments:
     * `name`
   * Optional arguments:
     * a list of segments, allocated with Segment()

 * `MultiTty`
   * Mandatory arguments:
     * `name`