From owner-freebsd-hardware Wed Mar 18 01:07:35 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id BAA01094 for freebsd-hardware-outgoing; Wed, 18 Mar 1998 01:07:35 -0800 (PST) (envelope-from owner-freebsd-hardware@FreeBSD.ORG) Received: from palrel3.hp.com (palrel3.hp.com [156.153.255.226]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id BAA01089 for ; Wed, 18 Mar 1998 01:07:31 -0800 (PST) (envelope-from darrylo@mina.sr.hp.com) Received: from srmail.sr.hp.com (srmail.sr.hp.com [15.4.45.14]) by palrel3.hp.com (8.8.5/8.8.5tis) with ESMTP id BAA12786; Wed, 18 Mar 1998 01:07:23 -0800 (PST) Received: from mina.sr.hp.com by srmail.sr.hp.com with ESMTP (1.37.109.16/15.5+ECS 3.3) id AA042642042; Wed, 18 Mar 1998 01:07:23 -0800 Received: from mina.sr.hp.com by mina.sr.hp.com with SMTP (1.37.109.16/15.5+ECS 3.3) id AA012672042; Wed, 18 Mar 1998 01:07:22 -0800 Message-Id: <199803180907.AA012672042@mina.sr.hp.com> To: Greg Lehey Cc: hardware@FreeBSD.ORG Subject: Re: CD-R and Scanner recomendations for CD archiving of records? Reply-To: darrylo@sr.hp.com In-Reply-To: Your message of "Wed, 18 Mar 1998 12:02:01 +1030." <19980318120201.47709@freebie.lemis.com> Mime-Version: 1.0 (generated by tm-edit 7.106) Content-Type: text/plain; charset=US-ASCII Date: Wed, 18 Mar 1998 01:07:21 -0800 From: Darryl Okahata Sender: owner-freebsd-hardware@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org Greg Lehey wrote: > On Tue, 17 March 1998 at 19:00:50 -0600, David Kelly wrote: > > > We've used about 400 blue Verbatim's at work so coated. You have to be > > careful when writing on the coated side else you'll ruin the disk. > > Apparently the layer written by the CD-R is just under the top coating. > > Am I missing something here? People keep talking about writing on the > coated side. Why would anybody want to do that? Surely you write on > the other side? I think everyone's getting confused with the terminology. You can write with a soft felt-tip pen on the top side of the disk -- the side that typically has the silk-screened (?) labels. As David wrote, you definitely do not want to use a hard-tip pen (such as a ballpoint) or a pencil. The top-side is very thin, and the data layer is easily damaged by pressure from any hard-tipped writing instrument. If you want to see something "scary", take a bad disk (or a CD that you don't mind losing), and lightly press your fingernail on the top side (the side with the label). Now, look at the bottom side, where your fingernail is lightly pressing from the other side. You'll see an extremely small "dot" where your fingernail is pressing against the disk; this is where the pressure is deforming the data layer. Move your finger around, and you'll see the "dot" move. If you press lightly, you probably won't damage the disk; if you press too hard, you'll do the same kind of damage that an hard-tipped instrument will do. It's amazing how little pressure can deform the data layer. This is also true of the stamped, mass-produced, aluminium CDs (such as compact audio disks). The silver CDs are just as susceptible to damage as the write-once or rewritable CDs. Still, for archival purposes, I'll trust a write-once CD made by a reputable manufacturer over tape, any day. However, the only real problem with CDRs is the low capacity (650MB). Yes, the writable DVD drives are supposed to fix this, but I'll believe that when the manufacturers deliver. If people are interested in more info, see: http://www.cd-info.com/CDIC/Technology/CD-R/FAQ.html In particular, see these for media life info: http://www.cd-info.com/CDIC/Technology/CD-R/FAQ07.html#[7-5] http://www.nml.org/Publications/TechnicalReports/MediaStability/DoculabsCDRCompatability/index.html -- Darryl Okahata Internet: darrylo@sr.hp.com DISCLAIMER: this message is the author's personal opinion and does not constitute the support, opinion, or policy of Hewlett-Packard, or of the little green men that have been following him all day. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message