At this point you have assembled the power supply, made the necessary connections from the serial port cable to the Stamp and have assembled and tested the logic probe. Note that the LEDs supplied with the Basic Starter package have an integrated 330 Ohm resistor to limit the LED current to nominally 10 mA. The idea is to force a logic one on an ouput for a period of time, thus turning the LED on. And then, output a zero for a period of time, causing the LED to turn off. Although not required, good programmers spend a bit of effort briefly describing the overall operation of the program and include annotations within the code to give the reader a clear idea of what the statements are doing. The word TOP is a label, in this case, a place in the program.
Labels can be virtually anything other than specific key words.
The Stamp reserves a 16-bit variable DIRS with the state of each bit being used to confgure that pin as either as an input or an output. Specific bits, may be selectively configured using the DIRp nomenclature. That is, DIR0 or DIR7 or DIR15. A one configures the bit as an output. Note that the time is in milliseconds.