_
              .----------/ |<=== floppy disk
             /           | |
            /           /| |          _________
           /           / | |         | .-----. |
          /___________/ /| |         |=|     |-|
         [____________]/ | |         |~|_____|~|
         |       ___  |  | |         '-|     |-'
         |      /  _) |  | |           |.....|
function ======>|.'   |  | |           |     |<=== application
  key    |            |  | |    input  |.....|       software
         |            |  | |            `--._|
  main =>|            |  | |      |                 de-bugging   ||
 storage |            |  | ;______|_________________   tool ====>||
         |            |  |.' ____\|/_______________ `.          ||
         |            | /|  (______________________)  )<== user  ||
         |____________|/ \___________________________/  interface||
         '--||----: `'''''.__                      |             ||
            || jgs `""";"""-.'-._ <== normal flow  |    central  ||
            ||         |     `-. `'._of operation /<== processing||
            ||         |        `\   '-.         /       unit    ||
  surge     ().-.      |         |      :      /`                ||
control ==>(_((X))     |      .-.       : <======= output        ||
 device       '-'      \     |   \      ;     /_________       .-''-.
                        `\  \|/   '-..-'      |   /_\  /|     /______\
                         /`-.____             |       / /      [____]
                        / _     /_____________| _    / /_
          peripherals ==>/_\___________________/_\__/ /~ )__
            (hardware) |____________________________|/  ~   ) |\\\ ///|
                                            (__~  ~     ~(~~` | \\V// |
          overflow (input/output error) ===> (_~_  ~  ~_ `)   |  |~|  |
      _________                                  `--~-' '`    |  |=|  |
   _|`---------`|                       supplemental data ===>|  | |  |
  (C|           |<=== back-up        (()____                  |  | |  |
   `\           /                   ('      `\______,          \ |=| /
     `=========`           mouse ==> `,,---,,'                  \|_|/