From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 23353 invoked from network); 4 Oct 2021 01:24:22 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 4 Oct 2021 01:24:22 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 356B09CBE9; Mon, 4 Oct 2021 11:24:18 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id AF78E9CAF1; Mon, 4 Oct 2021 11:23:47 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id EC9869CAF1; Mon, 4 Oct 2021 11:23:43 +1000 (AEST) Received: from oclsc.com (oclsc.com [206.248.137.164]) by minnie.tuhs.org (Postfix) with SMTP id 8B9AE9CAE9 for ; Mon, 4 Oct 2021 11:23:42 +1000 (AEST) Received: by lignose.oclsc.org (Postfix, from userid 1000) id C3404640CC6; Sun, 3 Oct 2021 21:22:20 -0400 (EDT) To: tuhs@tuhs.org Message-Id: <20211004012220.C3404640CC6@lignose.oclsc.org> Date: Sun, 3 Oct 2021 21:22:20 -0400 (EDT) From: norman@oclsc.org (Norman Wilson) Subject: [TUHS] Groups origins X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" Groups appeared surprisingly late (given how familiar they seem now): they don't show up in the manual until the Sixth Edition. Mea culpa; read too hastily. The change actually came with the Fourth Edition, at the same time as several other landmark system changes: -- Time changing from a 32-bit count of 60Hz clock ticks (which ran out so quickly that its epoch kept moving) to the modern 32 bits of whole seconds, based at 1970-01-01T00:00:00 GMT (which takes much longer to run out, though the horizon is now visible). -- The modern super-block. In 4/e, the super-block began at block 0, not 1 (so bootstrapping was rather more complicated); the free list was a bitmap rather than the later list of blocks containing lists of free block numbers. -- The super-block contained a bitmap of free i-numbers too. All told, the free block and free i-node map made up a 1024-byte super-block. -- I-numbers 1-40 were device files; the root directory was i-number 41. The only file-type indication in the mode word was a single bit to denote directory. It was already clear that the lifetime of the bitmaps was running out: the BUGS section says two blocks isn't enough for the bitmaps for a 20-megabyte RP02. Norman Wilson Toronto ON