In SX Microcontrollers, SX/B Compiler and SX-Key Tool, lajko wrote:

I built a set of boards that interface Brunswick Vector automatic scoring system cameras (yes, bowling) to old, ancient pinsetters.
I put programming pins for the key on the board and all ICs are socketed.
The A port is driven by 3 H11L1 opto isolators.
I find that when first powered on with an un-programmed SX-28, the H11L1's sometimes get fried. There is nothing on the LED input as it gets connected to opto isolators in the Brunswick camera module, so the frying must come from an extreme drain on the output connected to the A port of the SX-28.
Once the SX-28 is programmed, everything is OK. So I leave off the H11L1's until the SX-28 is programmed and I no longer fry any of them.
The SX-28 spec states all IO ports come up in the input mode on power on reset. But is that always the case when the SX-28 has never been programmed?

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