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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