test-drb November 2000

test-drb@ccmp.vtda.org

197 participants
507 discussions

by ajp166＠bellatlantic.net

From: Don Maslin <donm(a)cts.com> >particular, I recall reading about a '60ish project by one of Britain's >Formula One makers to use a computer to control a F1-machine driving >around an actual circuit in lieu of the driver. As I recall the story, >it did not make it beyond the second turn. However, an analogue >computer handled the task quite well. Apocryphal? ??? this confuses the ideas of precision, accuracy and speed with complexity. Digital is absolute accuracy IE: 0101=5 and for a given machine any variation is error. Analog, is mushy on accuracy, 5 Volts at some output is "approximate". Digital to process data for a complex equation in real time has to collect it perform operations on it and output it. These occur at some rate that is fixed by hardware. The more complex the task the lower the total Throughput will be. Also there is latentcy, time from input to processed output, more complex means longer for a fixed speed. Analog, assuming a fixed slew rate for the op-amps used the system throughput IE: a change in input means near immediate change in output that will be complete in some "setteling time". That time even for slow op-amps is quite fast and usually in microseconds. Also analog does not mean the output cant be absolute (IF Vin or Fin exceeds N (some rate) then turn relay on). I've done some really neat things using pots realys and motors with only limited use of amplifying devices to trans late the pots output to something that can drive a motor. This is classic servo systems stuff and the fundemental circuit is the Wheatstone bridge for systems like this. If you add nonlinear devices like LOG taper pots(variable resistors) and gears and cams you can get reactions that can mimic things like non linear actions. The idea of balance is employed. This kind of automation was as common as flies and widely seen though often as simple devices. There is another group of machines that fall dead smack in the middle of the analog and the digital. These were the early preprocessing boxes that might take 8 channles of analog telemetry data and reduce it to stored data based on time, sensor and relative value or even as a histogram. While these machines would have counters, registers and some even core or drum(disk) they were at best not programable and most didn't even qualify as hardwired program (elementary state machine). Just a few points about early computer differences. Allison

23 years, 10 months

HP 35401A Autoloader Tape Drive??

by ip500＠home.com

This should just make the 10 year rule...it had a service sticker on it >from 1988. Cool, robotic magazine fed tape drive that holds 8 of the DC600A 1/4" tape cassettes and autofeeds them into the drive. All of my old HP reference stuff lists mass storage gear under 79xx series rather than this 35401A business Anyone have any data on this beast? Catalog sheet or tech sheet would be ideal. It talks to the outside world via HPIB cable. Thanks, Craig

23 years, 10 months

HP DraftMaster I

by sumeetsuri＠psu.edu

Hi guys, I am sure I am very late in your discussion. Right now I am using the HP 9872 plotter and I need another piece. Could u tell me where I can find a HP 9872 plotter. Thanks a lot Sumeet

23 years, 10 months

MULTICS Installation, Halifax

by dhquebbeman＠theestopinalgroup.com

> >I should have mentioned that Multics also was closely tied > >to a 36-bit word size... a re-implementation could probably > >get around this, but a port would be difficult... > > > >However, a port would work for an emulator, where you'd have > >control of all aspects of the target architecture. > > Well.... Then How about one of the following Chips? Itanium, Alpha, > PA-RISC, or UltraSparc? Would a 64-bit computer be able to > handle running a 36-bit OS? Certainly... in fact, this topic generated some heat. It's my contention that being bottom-feeder commodity equipment, the Intel line would be more cost-effective than an Alpha. But that's irrelevantif you've got a box of surplus Alpha chips lying around. And the IA64 won't quite be bottom-feeder commidity for a year or two, at least. ;-) > On the emulator side there are definitly 36-bit systems emulated on 32-bit > chips, and even on 16-bit systems (at least IIRC, the 68000 is a 16-bit > chip). I'm still waiting to get my hands on one of these mythical PDP-10 emulators... I want my own DECSYSTEM-10, even if it's really running on an old Mac. regards, -dq

23 years, 10 months

reading a 9-track tape

by yoda＠isr.ist.utl.pt

Hi. Can anyone read a 9-track tape? I have a tape I'd like to read, but I have no tape drive for those tapes. I was wondering if anyone in europe could read it for me. Cheers, -- *** Rodrigo Martins de Matos Ventura <yoda(a)isr.ist.utl.pt> *** Web page: http://www.isr.ist.utl.pt/~yoda *** Teaching Assistant and PhD Student at ISR: *** Instituto de Sistemas e Robotica, Polo de Lisboa *** Instituto Superior Tecnico, Lisboa, PORTUGAL *** PGP fingerprint = 0119 AD13 9EEE 264A 3F10 31D3 89B3 C6C4 60C6 4585

23 years, 10 months

Fibre Channel-related items up for grabs

by jfoust＠threedee.com

I got these items in a batch of other surplus items and I'm trying to determine their use or value. If anyone on this list is interested, please send a note, or off to eBay they go. See http://www.threedee.com/optics/ for pictures and more detailed descriptions. One is a HP A3406A Fibre Channel Host Adapter. I wasn't able to find this part number on HP/Aligent's web site, and it produced few other web hits. This a HP-HSC card, as used in today's K-series of servers. It can sustain 1/4 gigabit rates. Another item is a HP 83441B SONET SDH reference receiver. Is this used in testing very high speed optical networking equipment? It supports 622 Mbps SONET OC-12 and SDH and STM-4. It has fiber input on one end and RF output on the other. Another interesting item is a 28-pin DIP that appears to be a 20 mw semiconductor laser. This is an XMT1300-1.2, an optical driver for Fibre Channel (FC-0). An optical fiber emerges from one end and terminates in a standard pigtail fiber connector. It is a 20 milliwatt, Class 3b semiconductor laser, probably GaAs, centered at 1300 nm. It was made in 1991, so I felt close enough to the 10-year rule to post. :-) It was made by BT&D Technologies (British Telecom + Dupont) in 1991, now part of Agilent Technologies, a Hewlett-Packard company. It is one of their "logic to light" transmitters. - John

23 years, 10 months

Here's one for the DEC engineers

by ajp166＠bellatlantic.net

From: Chuck McManis <cmcmanis(a)mcmanis.com> >Well, I've got to give a toast to the folks in DEC Engineering, it may be >that they had to deal with Field Circus screwing things up, but I for one >really appreciate that DEC used keyed connectors, and appropriate cables, >and sturdy hardware. I'm also glad that whomever designed the TQK70 did so >such that plugging it in backwards in the Q-bus does it no apparent harm. I Thank you from myself and all the other CSSE engineers. Those little details were part of requirements for serviceability that came from the Field Service side of the house and implemented in best technology by engineering. Brief DEC history about the group that was often known as product prevention. Customer Support Systems Engineering (CSSE) was an engineering arm that came into being back in the late 70s when DEC started to see more volume then quality. One of the first processes created by Field Circus was FA&T (factory assemble and test) was the starting point. The field and FA&T feedback went far in the 80s to eliminate the unreachable screws, scope required to setup, special tools and too many similar connectors. Allison

23 years, 10 months

An article on the ZX-81 kits still being sold in the US

by pete＠dunnington.u-net.com

On Nov 7, 16:09, Hans Franke wrote: > Not completely. There _are_ 2 KB kits around - as you may remember, > the ZX81 board was to be used with either two 2114 (1KB)or one > 6116(2KB). Not exactly; originally, it was a 2 x 2114 or 1 x 4118. Most UK ZX81s have a 4118, though some users did replace the 4118 with a 6116. I've never seen one originally fitted with a 6116, only upgrades (and I've seen a lot of ZX81s -- the workshop I was in at the time used to fix them by the bucketload). -- Pete Peter Turnbull Dept. of Computer Science University of York

23 years, 10 months

Analog vs Digital devices, was Magnetics

by ajp166＠bellatlantic.net

From: John Lawson <jpl15(a)panix.com> >meter, in real time. This may sound cumbersome today, but consider in >that in the mid fifties, digital computers were very, very expensive, >fairly rare, and every single problem required much analysis and coding, It would be 1979 before there was DSP fast enough to do a FIR filter digially for audio frequencies, Analog had been doing that for 30+ years. > PS: Anyone *really* interested in getting into analog computing might do >well to consider scarfing up a Heathkit EC-1 when possible.. they are >simple, small and portable, and have easily replaceable tubes, and having >(IIRC) 9 opamps, one can get quite elaborate with them. One could duplicate it using modern analog opamps and still solve the same problems. The best one I remember solved a bouncing ball, for varying gravity and rebound rates and "drew it" on an O'scope face. It was a Popular Electronics (maybe RE) design. Still very buildable. It's often forgotten that there were different op-amp designs that allowed things like four quadrant multiplcation, LOG and ANTILOG amps, CLIPPING, SUM, DIFFERNCE, ABSOLUTE VALUE when combined allow solutions of great speed with good accuracy. Allison

23 years, 10 months

Vax message as system locks up

by ajp166＠bellatlantic.net

From: Bill Bradford <mrbill(a)mrbill.net> >> %SYSTEM-I-MOUNTVER, R7VEFG$DIA0: is offline. Mount verification in progress. >> After that I get a red line on the drive indicator and anything I on the >> console never returns. >> Any ideas? I have used varios drives that can handle the 512byte sectoring and they work fine. I have two Tohsiba XM3201B and a XM3501B that works fine for VMS. So there are other drives that do work. Allison

23 years, 10 months

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test-drb November 2000