<div dir="ltr"><div class="gmail_default"><font face="arial, sans-serif">I can not say why it followed that naming convention, but it did.   The drives of that day were referred to as 19" technology since that's how they mounted.   FWIW:   Most manufacturers at the time used the same platter size as the original IBM 1311 (which as you pointed out was 14"), but not everyone, for instance, the <span style="color:rgb(51,51,51)">Fujitsu Eagle used 10.5-inch platter.</span>   FWIW:  I answered a bunch of this in: <a href="https://www.quora.com/How-do-hard-drives-get-smaller-and-smaller-in-size-bigger-and-bigger-in-capacity-every-year-when-the-fundamental-physical-processes-behind-them-do-not-change/answer/Clem-Cole" target="_blank">https://www.quora.com/How-do-hard-drives-get-smaller-and-smaller-in-size-bigger-and-bigger-in-capacity-every-year-when-the-fundamental-physical-processes-behind-them-do-not-change/answer/Clem-Cole</a> </font></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jul 1, 2019 at 8:52 AM Patrick Finnegan <<a href="mailto:pat@computer-refuge.org" target="_blank">pat@computer-refuge.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Jul 1, 2019 at 7:32 AM Clem cole <<a href="mailto:clemc@ccc.com" target="_blank">clemc@ccc.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">19” form factor for the disks drive fir the space in the 19” relay rack.  You’re right the platters themselves were smaller.  The disks were referred too by the mechanical FF.  19, 8, 5.25 etc.   <br><br></div></blockquote><div><br></div><div>But, 8" hard drives have 8" platters, and 5.25" hard drives have 5.25" platters. The casing on a the 5.25" drive in front of me is almost 6" wide. </div><div><br></div><div>Pat</div></div></div>
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