OTP is PROM, which is an EPROM with no window.

The pattern 'blown' into a ROM is done with metalisation layers during the
final stages of production, which means that you have to commit to a lot of
parts.

Rgds...

...Andy

At 13:32 17/02/99 -0500, you wrote:
>I just rec'd the new Microchip line card. Inside they have a new
>category of parts classified as "R" such as 12CR509. The only
>difference they show is that the "R" version is classified as  ROM
>where the others are listed as OTP/Flash. Many of course are not
>flash. OTP is ROM, so what are they getting at here? Or is this just
>another way to classify window parts?
>
>Thanks
>Jack Shidemantle
>Automation & Development Engineer
>YSI, Inc. USA
>