I found an old box with 4 ESP8266 module. I initially thought they were ESP8266 -05, but this chip only has 4 pins (with a separate ground) instead of 5 pins (with a separate ground). This is pretty old, so I'm wondering if it was a difference chipset before they upgraded it?
If anyone could give me any information (specifically schematics) for this thing, that'd be great.
Thanks!

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