Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site sdcrdcf.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!hao!hplabs!sdcrdcf!darrelj From: darrelj@sdcrdcf.UUCP (Darrel VanBuer) Newsgroups: net.unix-wizards Subject: Re: Maximum buffer size for read from magtape? Message-ID: <1362@sdcrdcf.UUCP> Date: Wed, 3-Oct-84 11:07:44 EDT Article-I.D.: sdcrdcf.1362 Posted: Wed Oct 3 11:07:44 1984 Date-Received: Sat, 6-Oct-84 02:26:50 EDT References: <2248@ucbvax.ARPA> <143@mplvax.UUCP> Reply-To: darrelj@sdcrdcf.UUCP (Darrel VanBuer) Distribution: net Organization: System Development Corp. R+D, Santa Monica Lines: 16 Summary: IBM 360/370 architecture machines can read and write tape blocks over 64k, but it's tricky; you have to write your own channel program (an I/O program). (In fact, you have to write your own to go over 32K-1, the OS treats lengths as 16 bit signed quantity; the hardware count field is 16 bit unsigned, but you can beat the limit by data chaining [a way to provide another address/ count pair for a continuation of an operation] -- Darrel J. Van Buer, PhD System Development Corp. 2500 Colorado Ave Santa Monica, CA 90406 (213)820-4111 x5449 ...{allegra,burdvax,cbosgd,hplabs,ihnp4,orstcs,sdcsvax,ucla-cs,akgua} !sdcrdcf!darrelj VANBUER@USC-ECL.ARPA