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HC705J1A bootloader programming cct needed

Question asked by Graham Pratt on Sep 7, 2014

Hi all. Doing an upgrade for a good customer to some boards I made for him way back in the late 90's using HC705J1A OTP micros. Luckily I still have a few of them. I remember that there is a method of programming them where you could put your code in a small eprom, strap it to the micro, power it up and the code would be copied over and away you go. Obviously not the way you would do it in a production environment but quite okay for doing just a few.

 

Does anyone still have a circuit for this, and any necessary instructions?

I don't want any PC connected setup, just a micro, eprom and a handful of connections between the two.

 

Regards,

JD

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