Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site brl-tgr.ARPA Path: utzoo!watmath!clyde!bonnie!akgua!mcnc!decvax!wivax!cadmus!harvard!seismo!brl-tgr!gwyn From: gwyn@brl-tgr.ARPA (Doug Gwyn) Newsgroups: net.unix-wizards Subject: Re: Maximum buffer size for read from magtape? Message-ID: <4957@brl-tgr.ARPA> Date: Sat, 29-Sep-84 11:22:41 EDT Article-I.D.: brl-tgr.4957 Posted: Sat Sep 29 11:22:41 1984 Date-Received: Mon, 1-Oct-84 07:25:00 EDT References: <2248@ucbvax.ARPA> Organization: Ballistics Research Lab Lines: 8 The problem is that the tape controller only has a 16-bit register for the byte count to be transferred (via DMA). The number 64K is indistinguishable from 0 using 16-bit arithmetic. Most DMA controllers I have seen would transfer 64K if their byte count register were loaded with 0, although the device driver may decide not to let you try this. Be advised that 80Kb far exceeds the ANSI maximum tape block size.