What are the differences between the NXT and the RCX? I know that the NXT is newer, but what features does it have that the RCX doesn't have, and vice versa (if the RCX has features that the NXT doesn't)?
|3 motor and 4 sensor ports||3 motor and 3 sensor ports|
|Has encoders integrated in its motors so that they can be used as servos||Would need an additional rotation sensor on a sensor port to use as servos|
|Uses RJ12 connectors with the latch offset to one side||Uses regular 9V connectors (2x2 with metal in studs)|
|Uses a direct USB cable or Bluetooth for connection||Uses infrared to communicate with PC via an IR tower connected by a serial (1.0, 1.1) or USB (2.0)|
|Graphical 100X64 matrix display||Small numerical display with many limits|
|Technic oriented - uses technic pieces (no studs)||System oriented (studs) with small amount of technic|
|Uses graphical programming language with many features1||Uses a limited graphical programming language (apparently can't even run on XP)|
|Can play 8Khz wav files||Can play simple tones|
|Uses 6 AA batteries very quickly||Uses batteries more slowly|
|256 KB of flash memory that can hold a max. of 64 files of varying types||32 KB of RAM that can store up to only 5 programs|
The original 1.0 version of RCX Brick had a 10v connection plug, but this was dropped from the later versions included in the Robotics Invention System 1.5. The NXT can use a rechargeable battery in place of the six AA batteries, and the rechargeable batteries also have a 10v transformer plug.
RCX retains its memory (including firmware) for a very limited time when not powered, just enough to change batteries. NXT uses flash memory and keeps it all when not powered.
1: Note that even powerful computers have trouble running big programs, and can easily mess them up. There exist many third-party systems for both RCX and NXT. Full list on Wikipedia.
The NXT can, with the use of an adapter cable, use the RCX sensors and motors, however the RCX can not use the NXT sensors and motors. The NXT brick, motors and sensors are larger than the RCX counterparts which makes them harder to implement into a size constrained construction. However as said, you can use the RCX motors/sensors instead with the NXT brick if wanted.
The NXT programming possibilities are far greater than the RCX, both in the official and third-party languages. It has far more RAM and CPU to work with, where the RCX is a bit limited in this regard.
There is a large selection of 3rd party NXT sensors, from highly sensitive light sensors to touch screens, WIFI and GPS sensors. The NXT simply more possibilities as it provides both an analog and digital interface to sensor developers. (And it can use all the RCX custom sensors too of course.) The NXT wires are however thicker and less flexible than the RCX wires, so they are a bit harder to hide/control in your construction. You can also get some pretty long RCX wires, up to 1.5m in length iirc.