Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!ucsd!ucsdhub!hp-sdd!hplabs!otter!hpcpbla!mark
From: mark@hpcpbla.HP.COM (Mark Simms)
Newsgroups: comp.periphs
Subject: Re: Programming HP tapedrives
Message-ID: <1450004@hpcpbla.HP.COM>
Date: 1 Feb 90 13:43:38 GMT
References: <2258@psueea.UUCP>
Organization: HP Computer Peripherals Bristol, UK
Lines: 29

>> How do you read the number of valid bytes in a partial block?

This is not possible.  

Whilst the 9144 and 9145 will write a partially full block when sent a
write that is not a multiple of 1024 bytes, the only way to detect
that this has happened is by monitoring the address by sending request
status commands to the drive.  It would be theoretically possible to
issue read commands of different lengths but the same address, each
followed by a request status command, to determine the length of a
known partial block.  This would be slow and could increase tape and
drive wear.

Without knowing your application or host computer system, it is hard
to be more helpful.

Mark

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Opinions expressed are my own and are not intended to be an official
statement by Hewlett-Packard Company
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Name:         Mark Simms
Position:     Software Development Engineer
Organization: Hewlett-Packard Computer Peripherals Division
Email US:     mark%hpcpbla@hplb.hpl.hp.com
      UK:     mark%hpcpbla@hplb.hp.co.uk
Address:      Filton Road, Bristol BS12 6QZ, United Kingdom
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