> Yes. A chip needs to be produced in the hundreds of thousands to make it
> really cost effective. Since the code in a ROM is part of it's physical
> structure, it has to be included as the chip is being made. Whereas an
> EPROM can be programmed after the fact. I think Randy uses OTP (One Time
> Programmable) EPROMs. This is a standard EPROM without the quartz window
> for UV erasing. High quality quartz is expensive and adds considerably to
> the cost of an EPROM. I know that several manufacturers used EPROMs. Usually
> the smaller software houses that couldn't afford to have ROMs manufactered.
ROMs like this, if I remember right, are called PROMs. Or, at least, chips
like them. While the physical theory behind them may be different, I'm
certain that PROMs and EPROMs are both burned in similar ways (with
supervoltages).
I could be mistaken if it turns out that it's cheaper to manufacture
EPROMs without the windows than it is to manufacture actual PROMs.
What I'd like to see is a reference to where I can see just how long EPROMs
and other decay-prone media will last. Some definitive study, or something.
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