From: roy@cybrspc.mn.org (Roy M. Silvernail)
Date: Tue, 17 Oct 95 15:39:27 PDT
To: loofbour@cis.ohio-state.edu (Nathan Loofbourrow)
Subject: Re: DalSemi: Add-Only Memory for Storage of Digital Cash
In-Reply-To: <199510171820.OAA24348@colon.cis.ohio-state.edu>
Message-ID: <951017.172824.4H9.rnr.w165w@cybrspc.mn.org>
MIME-Version: 1.0
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In list.cypherpunks, loofbour@cis.ohio-state.edu writes:

> And there's another item of note: each chip has a unique, etched,
> machine-readable serial number. What are the bets that Dallas
> Semiconductor can tell you who purchased that chip? Well, so much for
> an anonymous payment scheme based on *this* product.

Dallas might be able to tell who purchased them, but it's likely to have
been someone like Hamilton-Hallmark (a major parts distributor).
Whether the distributors are going to maintain the audit trail is
questionable at best.  It only takes one distributor to break the
chain of traceability, and audit trails cost money.

> * Gee, back in my day EPROMs were Eraseable; these folks mean instead
>   to indicate an Electrically Programmable chip, which sounds like a
>   good old PROM to me. Ahhh, acronyms...

This comes from the fact that PROMs are typically mask-programmed at the
fabrication stage.  EPROMS are programmed in the field.  And yes, if you
could get the top of the chip off cleanly, you could erase and reprogram
them.  (not likely, and hardly undetectable, but it's ever so slightly
possible)  More often, I see these devices called OTP (for One Time
Programmable).  In the more standard types (27C256, for example),
they're a fraction of the cost of the erasable ones.  Ceramic cases and
quartz windows are spendy.
- -- 
           Roy M. Silvernail     [ ]      roy@cybrspc.mn.org
PGP Public Key fingerprint =  31 86 EC B9 DB 76 A7 54  13 0B 6A 6B CC 09 18 B6
                Key available from pubkey@cybrspc.mn.org

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