Wow what? That shoudn't work should it

[alband]

If got a 28X wire up as normal except 1 thing:
The only power pin is not connected instead 5V is going into pin 21 (the next one up).
How can this possibly be working?
There is no jumper wire or anything.
?????????????

 

[BeanieBots]

Common problem. It's known as "parasitic" power.
Inputs (and outputs) effectively have diodes which go to Vcc and 0v.
Hence, if you apply a logic high to an un-powerd PICAXE, it will power up via the diode.

 

[hippy]

Once you have rewired your circuit, check operation of Output Pin 0 ( leg 21 ) to ensure it can go high and low. Connecting the power this way may have dameged the on-chip output driver. Hopefully not, but best to mark the chip as potentially damaged lest you run into a problem with Output Pin 0 in the future - if it hasn't damaged it, it could have weakened it and may one day fail or not work as expected which could get quite frustrating.

 

[alband]

Good idea - may have just saved me a lot of hastle, thanks.