[Simh] Which PDP-11 to choose

[Clem Cole]

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 Fujitsu Eagle used 10.5-inch platter.   FWIW:
I answered a bunch of this in:
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


On Mon, Jul 1, 2019 at 8:52 AM Patrick Finnegan <pat at computer-refuge.org>
wrote:

>
>
> On Mon, Jul 1, 2019 at 7:32 AM Clem cole <clemc at ccc.com> wrote:
>
>> 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.
>>
>>
> 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.
>
> Pat
>
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