diff --git a/README.md b/README.md
index df07188..ef6420d 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,12 @@
-# cc-rail-router
-Scripts for Computercraft-managed minecart railways.
+# CC-Rail-Router
+
+A system for using Computercraft to control minecart junctions and routing. It works by having a traveling portable computer send out messages as it's traveling, so that nearby managed switches are set automatically.
+
+The portable computer, usually held by the traveling player, will send out a message containing its route as a list of strings, like so:
+```lua
+{ "A", "C", "D", "V" }
+```
+
+The switch controller will reply then look for any pairs of branch segments that it has control of, and will switch them accordingly. So suppose we have a switch that connects line `C` to line `D`, then upon receiving the above message, it'll change its signal outputs to route trains accordingly from `C` to `D`.
+
+With this design, the switch controller and portable computer are completely stateless, and no two-way communication is needed.
diff --git a/router.lua b/router.lua
new file mode 100644
index 0000000..8571aae
--- /dev/null
+++ b/router.lua
@@ -0,0 +1,22 @@
+--[[
+This program should be installed on a portable computer with a wireless
+modem, to act as a routing beacon in conjunction with managed switches.
+]]--
+local modem = peripheral.wrap("back") or error("Missing modem.")
+
+local args = {...}
+
+local route = args
+print("Routing via:")
+for _, branch in pairs(route) do
+    print("  "..branch)
+end
+
+local function sendRoute(route)
+    modem.transmit(0, 42, route)
+end
+
+while true do
+    sendRoute(route)
+    os.sleep(1)
+end
diff --git a/switcher.lua b/switcher.lua
new file mode 100644
index 0000000..2416baf
--- /dev/null
+++ b/switcher.lua
@@ -0,0 +1,202 @@
+--[[
+This program is to be installed on a computer that controls a single rail
+junction. As a player with a portable computer approaches, that portable
+computer will be sending out a signal indicating their preferred switching
+configuration (the branch they're coming from, and the one they want to go to),
+and the junction's computer will then send a success reply.
+]]
+
+local CONFIG_FILE = "switch_config.tbl"
+local CHANNEL = 0
+local config = nil
+ 
+local modem = peripheral.wrap("top") or error("Missing modem")
+if not modem.isWireless() then error("Wireless modem required") end
+modem.open(CHANNEL)
+ 
+term.clear()
+term.setCursorPos(1, 1)
+print("Receiving routing commands on channel 0")
+
+-- Series of guided inputs for building a configuration file from user input.
+local function configSetupWizard()
+    local cfg = {range = 32, switches = {}}
+    term.clear()
+    term.setCursorPos(1, 1)
+    print("Switch Controller Config Setup Wizard")
+    print("-------------------------------------")
+    print("What range (blocks) does this switch have? Defaults to 32.")
+    local rangeStr = io.read()
+    if rangeStr then
+        local rangeInt = tonumber(rangeStr)
+        if rangeInt == nil or rangeInt < 1 or rangeInt > 128 then
+            print("Invalid range value. Should be a positive integer number. Got "..rangeStr)
+            return nil
+        end
+    end
+    print("How many switch configurations are there? Usually 1 for each possible path of travel.")
+    local switchCountStr = io.read()
+    if not switchCountStr then
+        print("Invalid switch configuration count.")
+        return nil
+    end
+    local switchCount = tonumber(switchCountStr)
+    if switchCount == nil or switchCount < 2 or switchCount > 32 then
+        print("Invalid switch configuration count. Expected a positive integer between 2 and 32.")
+        return nil
+    end
+    for i = 1, switchCount do
+        local sw = {from = nil, to = nil, controls = {}}
+        print("Switch Configuration #"..i..":")
+        print("What is name of the branch traffic comes from?")
+        sw.from = io.read()
+        print("What is the name of the branch traffic goes to?")
+        sw.to = io.read()
+        print("How many control points are needed for this switch configuration?")
+        local controlCountStr = io.read()
+        local controlCount = 0
+        if controlCountStr then controlCount = tonumber(controlCountStr) end
+        if not controlCount or controlCount < 1 then
+            print("Invalid control point count. Expected a positive integer.")
+            return nil
+        end
+        for c = 1, controlCount do
+            local ctl = {type = "redstone", side = "top", state = true}
+            print("  Control Point #"..c..":")
+            print("  What type of control is this?")
+            print("  1. redstone")
+            print("  2. redstoneIntegrator")
+            local typeStr = io.read()
+            if not typeStr or typeStr == "1" or typeStr == "redstone" then
+                ctl.type = "redstone"
+                print("  What side is redstone output on?")
+                ctl.side = io.read()
+                print("  What state should the output be? [T/F]")
+                local stateStr = io.read()
+                ctl.state = stateStr == "T" or stateStr == "True" or stateStr == "t" or stateStr == "true"
+            elseif typeStr == "2" or typeStr == "redstoneIntegrator" then
+                ctl.type = "redstoneIntegrator"
+                print("  What is the peripheral name?")
+                ctl.name = io.read()
+                print("  What side is output on?")
+                ctl.side = io.read()
+                print("  What state should the output be? [T/F]")
+                local stateStr = io.read()
+                ctl.state = stateStr == "T" or stateStr == "True" or stateStr == "t" or stateStr == "true"
+            else
+                print("  Unsupported control type.")
+                return nil
+            end
+            table.insert(sw.controls, ctl)
+        end
+        table.insert(config.switches, sw)
+    end
+    local f = io.open(CONFIG_FILE, "w")
+    f:write(textutils.serialize(cfg))
+    f:close()
+    return cfg
+end
+
+local function loadConfig()
+    if fs.exists(CONFIG_FILE) then
+        local f = io.open(CONFIG_FILE, "r")
+        local cfg = textutils.unserialize(f:read("*a"))
+        f:close()
+        print("Loaded configuration from file:")
+        print("  "..tostring(#config.switches).." switch configurations.")
+        print("  "..tostring(config.range).." block range.")
+        return cfg
+    else
+        print("File "..CONFIG_FILE.." doesn't exist. Start setup wizard? [y/n]")
+        local response = io.read()
+        if response == "y" or response == "Y" or response == "yes" then
+            return configSetupWizard()
+        else
+            return nil
+        end
+    end
+end
+
+local config = {range=32, switches={}}
+if fs.exists(CONFIG_FILE) then
+    local f = io.open(CONFIG_FILE, "r")
+    config = textutils.unserialize(f:read("*a"))
+    f:close()
+    print("Loaded config:")
+    print("  "..tostring(#config.switches).." switch configurations")
+    print("  Range of "..tostring(config.range).." blocks")
+else
+    local f = io.open(CONFIG_FILE, "w")
+    f:write(textutils.serialize(config))
+    f:close()
+    print("Saved config to "..CONFIG_FILE)
+end
+
+local function findSwitchConfiguration(cfg, from, to)
+    if from == nil or to == nil then return nil end
+    for _, sw in pairs(cfg.switches) do
+        if sw.from == from and sw.to == to then return sw end
+    end
+    return nil end
+end
+
+local function isSwitchConfigurationActive(sw)
+    for _, control in pairs(sw.controls) do
+        if control.type == "redstone" then
+            local state = redstone.getOutput(control.side)
+            if state ~= control.state then return false end
+        elseif control.type == "redstoneIntegrator" then
+            local state = peripheral.call(control.name, "getOutput", control.side)
+            if state ~= control.state then return false end
+        else
+            error("Invalid control type: "..control.type)
+        end
+    end
+    return true
+end
+
+local function activateSwitchConfiguration(sw)
+    print("Activating switch: FROM="..sw.from..", TO="..sw.to)
+    for _, control in pairs(sw.controls) do
+        if control.type == "redstone" then
+            redstone.setOutput(control.side, control.state)
+        elseif control.type == "redstoneIntegrator" then
+            peripheral.call(control.name, "setOutput", control.side, control.state)
+        else
+            error("Invalid control type: "..control.type)
+        end
+    end
+end
+ 
+-- Handles incoming rail messages that consist of a list of branch names
+-- that the user would like to traverse.
+local function handleModemMsg(replyChannel, msg)
+    -- Ignore invalid messages.
+    if not msg or #msg < 2 then return end
+    -- Find the switch configuration(s) that pertain to this route.
+    for i = 1, #msg - 1 do
+        local sw = findSwitchConfiguration(config, msg[i], msg[i+1])
+        if sw and not isSwitchConfigurationActive(sw) then
+            activateSwitchConfiguration(sw)
+        end
+    end
+end
+
+config = loadConfig()
+if not config then
+    print("Unable to load configuration. Exiting.")
+    return
+end
+
+while true do
+    local event, p1, p2, p3, p4, p5 = os.pullEvent()
+    if event == "modem_message" then
+        local channel = p2
+        local replyChannel = p3
+        local msg = p4
+        local dist = p5
+        if channel == CHANNEL and dist ~= nil and dist < config.range and msg ~= nil then
+            handleModemMsg(replyChannel, msg)
+        end
+    end
+end
\ No newline at end of file