The ICSPDAT (data) pin is bi-directional, so there's a problem if 2 chips give a different response. Just wiring them together is probably not a good idea.

However, there may be a way. I've never done this, so take it with a grain of salt.


Theoretically, identical chips should give identical responses, unless there is an error. So if only 1 device is allowed to send to the programmer, the rest should follow along blindly.

But, if there's a programming error on any of the other chips, you'll never know.
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