From nobody Fri May 20 01:30:10 2022 X-Original-To: freebsd-questions@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id A4EC61AEA33B for ; Fri, 20 May 2022 01:30:13 +0000 (UTC) (envelope-from johnl@iecc.com) Received: from gal.iecc.com (gal.iecc.com [IPv6:2001:470:1f07:1126:0:43:6f73:7461]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "gal.iecc.com", Issuer "Let's Encrypt Authority X3" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4L48Kw5NcTz4VQ6 for ; Fri, 20 May 2022 01:30:12 +0000 (UTC) (envelope-from johnl@iecc.com) Received: (qmail 79651 invoked from network); 20 May 2022 01:30:12 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=simple; d=iecc.com; h=date:message-id:from:to:cc:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:cleverness; s=13721.6286ef24.k2205; bh=RwVOW9fxBJebZJPMbdn1VZy7Op/liM3D4PjSmE81wto=; b=LMcSCfMG40j4KKEzE4PJGPW2Kk/r9LwgHkW0177X63+UigGHrwT8/jmERSvN/7vXfTKVWMXRWdOYyy9DtXx7IvDHpL0+Z529FzOnfUi5wIzBjikXrPIZ20yi8rHxj3navQ36Ik08jPi5t58TJb1ADsnw8+Ef0JVF15O4oah/qQAQMwG52v7iB7bHq5AUEomFbidaqz8gjdAncHNS30pF8OO2cDX7rX1/Qk5Wjp6CsZeb1fDsMVCsTKuqbTtWYf3XsW3bNWuwcYHPYaUjDbM/bMoex9j7FzpNqtyd7l/qULb4Cx/lnrSnlCX0CdS0ihzOFDnQ4Xwbj+D1hpRlZPhJ4w== Received: from ary.qy ([IPv6:2001:470:1f07:1126::78:696d:6170]) by imap.iecc.com ([IPv6:2001:470:1f07:1126::78:696d:6170]) with ESMTPS (TLS1.3 ECDHE-RSA AES-256-GCM AEAD) via TCP6; 20 May 2022 01:30:11 -0000 Received: by ary.qy (Postfix, from userid 501) id 1DD2A414ABF9; Thu, 19 May 2022 21:30:10 -0400 (EDT) Date: 19 May 2022 21:30:10 -0400 Message-Id: <20220520013011.1DD2A414ABF9@ary.qy> From: "John Levine" To: freebsd-questions@freebsd.org Cc: steve@sohara.org Subject: Re: Tape, was Single User In-Reply-To: <20220519223448.e1db4297aef551734852e4fd@sohara.org> Organization: Taughannock Networks X-Headerized: yes Cleverness: minimal List-Id: User questions List-Archive: https://lists.freebsd.org/archives/freebsd-questions List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-questions@freebsd.org X-BeenThere: freebsd-questions@freebsd.org Mime-Version: 1.0 Content-type: text/plain; charset=utf-8 Content-transfer-encoding: 8bit X-Rspamd-Queue-Id: 4L48Kw5NcTz4VQ6 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=none ("invalid DKIM record") header.d=iecc.com header.s=13721.6286ef24.k2205 header.b=LMcSCfMG; dmarc=pass (policy=none) header.from=iecc.com; spf=pass (mx1.freebsd.org: domain of johnl@iecc.com designates 2001:470:1f07:1126:0:43:6f73:7461 as permitted sender) smtp.mailfrom=johnl@iecc.com X-Spamd-Result: default: False [-2.79 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; FROM_HAS_DN(0.00)[]; MV_CASE(0.50)[]; R_SPF_ALLOW(-0.20)[+ip6:2001:470:1f07:1126::/64]; MIME_GOOD(-0.10)[text/plain]; TO_DN_NONE(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; HAS_ORG_HEADER(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_IN_DNSWL_MED(-0.40)[2001:470:1f07:1126:0:43:6f73:7461:from,2001:470:1f07:1126:0:78:696d:6170:received]; RCPT_COUNT_TWO(0.00)[2]; DMARC_POLICY_ALLOW(-0.50)[iecc.com,none]; DKIM_TRACE(0.00)[iecc.com:~]; R_DKIM_PERMFAIL(0.00)[iecc.com:s=13721.6286ef24.k2205]; MLMMJ_DEST(0.00)[freebsd-questions]; NEURAL_HAM_SHORT(-0.09)[-0.087]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_TWO(0.00)[2]; ASN(0.00)[asn:6939, ipnet:2001:470::/32, country:US]; RCVD_TLS_ALL(0.00)[] X-ThisMailContainsUnwantedMimeParts: N It appears that Steve O'Hara-Smith said: >On 19 May 2022 20:49:51 -0000 >"John Levine" wrote: > >> The thing in the picture isn't paper tape, it's a 1/2" magnetic tape. >> It looks relatively new, 1970s rather than 1950s so it is likely >> recorded 9 bits across (8 plus parity) at a density of 1600 or 6250 BPI. > > I didn't look at the picture. That could be a *lot* harder to read >even if you have a drive. I've heard tell of tapes that could only be read >once due to storage damage rendering them more than a little fragile. I would be surprised if it were readable at all. After fifty years the oxide can come unglued from the backing, and there is a lot of magnetic print-through between adjacent layers of tape. It was common knowledge that if you cared about your tape files, you needed to recopy and verify them every so many years.