From mboxrd@z Thu Jan 1 00:00:00 1970 From: bqt@softjar.se (Johnny Billquist) Date: Tue, 10 Oct 2006 11:05:30 +0200 Subject: [pups] thrust meter? In-Reply-To: <1AC552DD-C287-4001-A5BC-95DD1092ACA8@psych.usyd.edu.au> References: <452424F9.28243.1AB56C7E@brian.quarterbyte.com> <1AC552DD-C287-4001-A5BC-95DD1092ACA8@psych.usyd.edu.au> Message-ID: <452B625A.1070304@softjar.se> 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 >>>Lab >>>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. Johnny