Need help understanding TTL logic; inverter?

Question

Hello, I was trying to understand the basic TTL inverter and how it works. You can go here http://www.play-hookey.com/digital/experiments/ttl_inverter.html to see an image. I'll refer to the transistor on the left as (1) and the one on the right as (2). So basically if a LOW is on the input, the diode junction(1) is forward biased, causing the current to flow AWAY from the base(2) which causes transistor(2) to be "off" meaning no current flow from collector(2) to emitter(2) causing the output to stay HIGH. If the input is HIGH, the diode junction (1) does not get forward biased, causing reverse current (?) to flow into the base(2), turning transistor(2) into saturation treating it nearly as a short and putting the output to LOW.

Is this right? Is the part about the reverse current to flow into base (2) correct? can you explain it any better??

Answer 1

If In is 0, as you described, the base of transistor 2 will be tied to ground (zero), there is no current flowing in transistor 2, so out is high.

If in is high, base of transistor 2 goes high, which allows current to go from the 5V source, through the 1K register to ground, which in effect ties Out to 0.