We really should take this off-list if you want to continue the discussion as it has little to do with simh and more history (so I'm CCing the TUHS COFF list. I'll include simh for now, but if you reply please kill the simh part).

An Eagle or Eagle-II was a whole lot lighter (and physically smaller) than an RP06 or RP07 (or an RM series drive for that matter). It is interesting to hear you had problems with the Eagles. They were generally considered the best/most reliable of the day. The SI controller on the Vax was less so, although many of us in the UNIX community used them.

FWIW: I was accused of jinxing the 19" SMD Ampex drive by Masscomp's field service team. The story is we could never make the Ampex drives work reliably at UCB (they were cheaper in bytes/$ than the Eagles at the time). When I was being recruited to Masscomp as I was leaving UCB, they were trying to use Ampex as their high-end SMD drive with the Xylogic 440 controller, but had not (yet) had a failure. [Xylogic, like Masscomp, was ex-DEC folks]. Anyway, I had mentioned @ UCB we had given up on the Ampex drive on our Vaxen, and within 2 weeks of my starting to work darned near all of them that Masscomp owned had failed.

PC (Paul Cantrell), tjt and I did eventually make them work but only after we got Xylogic to redesign the 440 to be the 450 controllers and PC spend hours with the microcode team on the error recovery logic. Funny, the 450/Eagle combination (and later Xylogic 472 tape) became the de rigor in the UNIX community.

BTW: if Mark and the simh team is to ever to create a solid Sun/Masscomp/Apollo simulator, they will need to emulate the Xylogic controller family. One more thing for the forever growing list of things I'd like to do when I retire, but I think I still have the engineering specs for them and PC and tjt are still to be found ;-)

On Mon, Jul 1, 2019 at 9:19 AM Tim Wilkinson <tjw@twsoft.co.uk> wrote:

Back in 85 have had applications to purchase a 785 – 780-750-730 then 725 rejected, we were fortunately given a 750 by a sister company who were upgrading to a 785, but they took their disks. So we had to buy for ourselves.

To keep the bean counter happy we went for a System Industries controller and 4 super Eagles.

But back then there was a problem with the eagles and all 4 had to be swapped out 4 times.

Carrying them up stairs to the computer room was not fun. The platter size may have been reduced. But the weight!!!

Tim
From: Simh [mailto:simh-bounces@trailing-edge.com] On Behalf Of Clem Cole
Sent: 01 July 2019 14:08
To: Patrick Finnegan <pat@computer-refuge.org>
Cc: SIMH <simh@trailing-edge.com>
Subject: Re: [Simh] Which PDP-11 to choose

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@computer-refuge.org> wrote:

On Mon, Jul 1, 2019 at 7:32 AM Clem cole <clemc@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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