dave cox
Re: Non-working Commodore PET 3016
A little OT, but I managed to remove the top from a TMS25P32. It certainly looks like an EPROM inside.
Was it really cheaper to make with a lid than with a window or is it just an anti-recycling / anti re-flashing measure ?
SiriusHardware
Re: Non-working Commodore PET 3016
Maybe those windows were a bit more expensive than the plain lid (the material had to be UV-transparent, I guess, so possibly not ordinary glass).
Quote:
Originally Posted by dave cox
Indeed, usually silica glass is used if you need UV transparent. I don't recall it being super expensive, unless you are comparing it to window glass!
dc
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I thought they had to use Quartz, for UV transparency, and this did make it more expensive - like EPROM-Eraser tubes, that were like cheaper fluorescent ones without the coating and with special Mica? glass.
The ceramic package, needed for compitability with glass windows, also made these more expensive than plastic-package types of later OTP ones.
Although even if still in a ceramic package, but with non-transparent window, these OTP ones were probably a bit cheaper - the main reason why OTP types would have been used.
But maybe there hadn't been enough demand / alternative packaging process developed yet, for OTP versions of the 2732 so they just swapped the window-cover. The covers on this type does sometimes fall-off, with glue failure, and later ones tend to have a circular windowed embedded in the hole, flush with the surface.
It seems the very first non fusible-link 1601 etc. PROM's used the same silicon die as the slightly-later 1701 etc. EPROM's. But had a soldered-on metal lid, before they developed UV-transparent ones. Although there is rumour you might be able to erase the metal-lid ones with the right x-ray source (if it doesn't damage the IC)