[sdiy-interim] EPROM Armageddon?

[Robin Whittle]

Paul wrote:

> a) Any synth with EPROMs older than 20yrs is living on "borrowed time".

I agree that it is worth keeping a backup copy of the data, but I don't
think anyone should think their EPROM data is suddenly going to fade
away at any particular age.


> You are really screwed if you have an OTP (one time programmable) CPU,
> like a TB-303. 

The TB-303, TR-606, TR-808 etc. CPUs are mask-programmed 4 bit NEC
devices.  There is no EPROM, so the data does not depend on stored
charge and should never fade away.  There must be a test mode for
reading the ROM data, but I don't know what it is.  There are no chips
like this being manufactured, and I don't think they made an EPROM
version anyway.


> If you have external EPROMs, I suggest copying them, and
> reprogramming. 

I would copy the data into a fresh set of chips, test them, and then
keep one set as a spare.


  - Robin


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