[Info-vax] OT: the Daily WTF for today is a VAX/VMS story

[Johnny Billquist]

On 2016-02-15 00:05, William Pechter wrote:
> In article <cld7pc-g5j1.ln1 at news.chingola.ch>,
> Paul Sture  <nospam at sture.ch> wrote:
>> On 2016-02-14, JF Mezei <jfmezei.spamnot at vaxination.ca> wrote:
>>> On 2016-02-14 04:48, already5chosen at yahoo.com wrote:
>>>
>>>> More I think about it, more the story of VAX hard drive with
>>>> three-phase AC motor (in early 90s, non-the-less) appears apocryphal.
>>>
>>>
>>> RA82 drive motors were 1/3 horsepower motors. They were not 3 phase, but
>>> required 3 wires in. There was one used to start the motor in the right
>>> direction as I recall.  There was some capacitor that would discharge to
>>> get motor going. I don't recall the exact details.
>>
>> I know nothing about the wiring details, but two or more RM05 drives could
>> be connected together so that they spun up in sequence to minimise the
>> maximum current draw.
>>
>> And yes, I had a customer who reported that as a hardware error :-(
>>
>> --
>> There are two hard things in computer science: cache invalidation,
>> naming, and off-by-one errors.
>
> Yup and the RP06's could even share a power socket with a cable DEC shipped
> that let a pair of drives daisy-chain the AC power between them.
>
> And a power sequence cable kept them from trying to power up at the same time
> IIRC...

You know, I've never seen a power sequence cable for the RP06, but when 
I was reading the documentation now, the manual mentions the power 
sequence control. So obviously there must have been a way to connect 
them together for that purpose.

Our DEC-2060 had three RP06, but I cannot remember any power sequencing 
going on between them. But maybe 3 was considered too few. Or, actually, 
I think we also had them all on separate fuses...

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
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