Reply to post: Re: Isolation

'The capacitors exploded, showering the lab in flaming confetti'

DropBear Silver badge

Re: Isolation

...except the extension connector on the back of the Spectrum was gold-plated PCB traces ("fingers") of the CPU's bus, as-is, and building something that would properly galvanically isolate it while still doing bidirectional I/O at 3.5MHz, while not impossible, was at the time not a practical option for 99.999999% of its owners. Anything less would only have been buffering, hopefully protecting against back-driving the bus but not against any "funny" voltages. So what you actually did instead was design stuff carefully and properly the first time*!

* let's not get into risk multipliers caused by the appropriate PCB-edge connector being unavailable and fabricating your own from two other pieces of PCB comb-slit into flexible-ish individual contacts for each finger, with a bit of wire soldered onto for better-than-PCB-on-PCB contact. Yes, I did get a Kempston joystick interface out of it and yes, I was definitely wearing my brown pants when I first powered the thing up...

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