The ESP-01 is a little tricky to use because it only has two GPIO pins (GPIO0 and GPIO2) and the settings on those two pins effect whether the module is running the sketch or whether you will be uploading a new sketch.
This is explained in Chapter 4 of Pieter's tutorial paragraph Boot Modes.
https://tttapa.github.io/ESP8266/Chap04%20-%20Microcontroller.html
http://www.forward.com.au/pfod/ESP8266/GPIOpins/index.html describes "tricks" on how to use the ESP-01.
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