[pups] thrust meter?

Johnny Billquist bqt at softjar.se
Tue Oct 10 19:05:30 AEST 2006

John Holden wrote:
> On 05/10/2006, at 10:15 PM, Dave Horsfall wrote:
>>On Wed, 4 Oct 2006, Brian Knittel wrote:
>>>The thrust meter project -- was that an analog meter that displayed %
>>>CPU utilization? I remember that Tom Ferrin had one mounted in the
>>>middle of a DEC panel filler on the 11/70 at the Computer Graphics  
>>>at UCSF. It was really delightful having this analog meter  
>>>bouncing up
>>>and down as people worked away.
>>It integrated the BUS BUSY signal over a suitable time constant  
>>(and my
>>electronics knowledge is a bit too rusty to figure out Tc, but with a
>>10uF tantalum capacitor I imagine it would be a few seconds).
> Um, depends what you mean by thrust. It was originally designed for a  
> 11/45
> where bus activity would have been a fare indication of machine load  
> since
> all memory and i/o used the unibus (I'm excluding the effects of fastbus
> memory on 11/50 and 55's).
> The 11/70 unibus was actually slower than the 11/45, and generally  
> didn't
> have memory or disk/tape i/o on it (separate memory bus and massbus). So
> 'thrust' was probably mainly character i/o (dh and dz's) and older
> disk/tapes (RK05's etc)
> Now, where's 11/70 maintenance printset?

I got them here. :-)

Hmm, but yeah. Since the bus might be idle even though the CPU is 
running, you might not get a very good reading by looking at the unibus.
But I think there are other signals that would be better to integrate 
over. Such as the MASTER lamp (or is it the CPU lamp perhaps?) of the 
front panel.


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