KNS wrote:My key requirement is that the statement for ON or OFF be executed within a few milliseconds (the shorter the better).
How far do you want to go? Phidgets and the 1032 is a very good choice for controlling LEDs, but the system uses USB on a desktop OS (which does put limits on expected response time).
Right now I am working on a small hobby project involving an Atmel XMEGA and a MAX7219. The XMEGA Event System guarantees response time of two cycles(!) at 32MHz, and the MAX7219 controls 64 LEDs over a 10MHz serial interface. Using hardware for well below $50 (including microcontroller and LEDs) I can toggle individual LEDs in the 0.1ms range. But coding it is a nightmare, debugging is close to impossible and the hardware resources are extremely limitted. You can have an RTOS if you want it, but I would be surprised if Phidgets and 1032 is not by far your best choice.