diff --git a/gps/gpsServer.lua b/gps/gpsServer.lua
index 5dc278f..dc2d354 100644
--- a/gps/gpsServer.lua
+++ b/gps/gpsServer.lua
@@ -3,9 +3,11 @@ local GPS    = require('gps')
 local Util   = require('util')
 
 local args       = { ... }
+local fs         = _G.fs
 local gps 			 = _G.gps
 local os         = _G.os
 local peripheral = _G.peripheral
+local read       = _G.read
 local term       = _G.term
 local turtle     = _G.turtle
 local vector     = _G.vector
@@ -14,11 +16,13 @@ local WIRED_MODEM = 'computercraft:wired_modem_full'
 local CABLE       = 'computercraft:cable'
 local ENDER_MODEM = 'computercraft:advanced_modem'
 
+local STARTUP_FILE = 'usr/autorun/gpsServer.lua'
+
 local positions = { }
 
 local function build()
-	if not turtle.has(WIRED_MODEM, 8) or
-		 not turtle.has(CABLE, 4) or
+	if not turtle.has(WIRED_MODEM, 5) or
+		 not turtle.has(CABLE, 8) or
 		 not turtle.has(ENDER_MODEM, 4) then
 		error([[Place into inventory:
  * 5 Wired modem (blocks)
@@ -26,6 +30,18 @@ local function build()
  * 4 Ender modems]])
 	end
 
+	term.clear()
+	term.setCursorPos(1, 2)
+	term.setTextColor(colors.yellow)
+	print('    Turtle must be facing east\n')
+	term.setTextColor(colors.white)
+	print(' Enter to continue or ctrl-t to abort')
+	read()
+
+	term.clear()
+	term.setCursorPos(1, 2)
+	print('building...')
+
 	local blocks = {
 		{ x =  0, y = 0, z =  0, b = WIRED_MODEM },
 
@@ -55,6 +71,41 @@ local function build()
 	end
 end
 
+local function configure()
+	local function getOption(prompt)
+		while true do
+			term.write(prompt)
+			local value = read()
+			if tonumber(value) then
+				return tonumber(value)
+			end
+			print('Invalid value, try again.\n')
+		end
+	end
+
+	print('Server configuration\n\n')
+
+	Config.update('gpsServer', {
+		x = getOption('Turtle x: '),
+		y = getOption('Turtle y: '),
+		z = getOption('Turtle z: '),
+		east = getOption('East modem: modem_'),
+		south = getOption('South modem: modem_'),
+		west = getOption('West modem: modem_'),
+		north = getOption('North modem: modem_'),
+	})
+
+	print('Make sure all wired modems are activated')
+	print('Enter to continue')
+	read()
+
+	if not fs.exists(STARTUP_FILE) then
+		Util.writeFile(STARTUP_FILE,
+			[[shell.openForegroundTab('gpsServer.lua server')]])
+		print('Autorun program created: ' .. STARTUP_FILE)
+	end
+end
+
 local function memoize(t, k, fn)
 	local e = t[k]
 	if not e then
@@ -65,19 +116,32 @@ local function memoize(t, k, fn)
 end
 
 local function server()
-	local modems = Config.load('gpsServer')
 	local computers = { }
 
-	if Util.empty(modems) then
-		error('Missing usr/config/gpsServer configuration file')
+	if not fs.exists('usr/config/gpsServer') then
+		configure()
 	end
 
+	local config = Config.load('gpsServer')
+
+	local modems = { }
+	modems['modem_' .. config.east]  = { x = config.x + 2, y = config.y + 2, z = config.z     }
+	modems['modem_' .. config.west]  = { x = config.x - 2, y = config.y + 2, z = config.z     }
+	modems['modem_' .. config.south] = { x = config.x,     y = config.y,     z = config.z + 2 }
+	modems['modem_' .. config.north] = { x = config.x,     y = config.y,     z = config.z - 2 }
+
 	for k, modem in pairs(modems) do
-		Util.merge(modem, peripheral.wrap(k))
+		Util.merge(modem, peripheral.wrap(k) or { })
+		Util.print('%s: %d %d %d', k, modem.x, modem.y, modem.z)
+		if not modem.open then
+			error('Modem is not activated or connected: ' .. k)
+		end
 		modem.open(gps.CHANNEL_GPS)
 		--modem.open(999)
 	end
 
+	print('\nStarting GPS Server')
+
 	local function getPosition(computerId, modem, distance)
 		local computer = memoize(computers, computerId, function() return { } end)
 		table.insert(computer, {
@@ -123,23 +187,9 @@ if args[1] == 'build' then
 	build()
 	turtle._goto({ x = 0, y = 1, z = 0, heading = 0 })
 
-	print('Activate all modems')
-	print('Press enter when ready')
-	_G.read()
+	configure()
 
-	local modems = { }
-	peripheral.find('modem', function(name, modem)
-		if modem.isWireless() then
-			modems[name] = { x = 0, y = 0, z = 0 }
-		end
-	end)
-
-	Config.update('gpsServer', modems)
-
-	print([[
-Configuration file usr/config/gpsServer created.
-Add coordinates for each modem.
-Use the position of the wired modem below the wireless modem]])
+	server()
 
 elseif args[1] == 'server' then
 	server()