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101090 discussions

Another thought on 10baseT vs 10Base2: was Re: Microvaxen bits etc.

by go＠ao.com

I just had to stick in my 2.1 cents worth (inflation, you know...) on this issue. I will *never again* use 10base2 for plant wiring for the simple reason that 10base2 (and 10base5) provide a ready path for "ground loops" between all the equipment sharing the cable. It's true that the "grounds" are "supposed" to be isolated (to the tune of several Kvolts) from the computer connection, but, believe me: "sh*t happens." And the results can be dangerous. 10baseT is designed to be isolated at every connection point in the "star" configuration (high-isolation transformer coupling,) so there is a much less likely path for the "big ugly voltage" from one piece of defective equipment that just happens to be shorted to the Ethernet 10base2 cable. You don't get killed when you reach behind your computer and grab the Ethernet cable and suddenly find it has 480vac on it due to some stupid short in a control cabinet. If the 10baseT cable is shorted, the hub has a high potential, but it never makes it out to any of the other cables plugged into the hub. Both of these scenarios assume correctly isolated cable-to-interface connections. It's just there is nothing isolating the bad stuff from you when you touch the cable shield. The necessary hub on 10baseT keeps the bad stuff from getting past the first short - assuming you *do* use a hub... And making 10baseT connections (with the proper 50US$ tool) is MUCH FASTER than making coax connections, if speed is important. Of course, the better (best?) approach is 10baseF, but it isn't readily available for us with home installations (at least not at the price *I* want to pay.) Gary

27 years, 10 months

Noise levels have become deaf

by roblwill＠usaor.net

Exactly what I do to other loud-mouthed salesmen. If they want to babble about crap, go the the neighbor's house. -Jason *********************************************** * Jason Willgruber * * (roblwill(a)usaor.net) * * * * http://members.tripod.com/general_1 * * ICQ#-1730318 * * /0\/0\ * * > Long Live the 5170! * * \___/ * ************************************************ ---------- > From: Bill Richman <bill_r(a)inetnebr.com> > To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> > Subject: Re: Noise levels have become deaf > Date: Wednesday, October 28, 1998 10:55 AM > > Hmm... Looks like Sweet Sam decided that if he couldn't shout me down, he'd > just slam the door in my face. What a guy! > > --- > > Return-Path: <listproc(a)u.washington.edu> > Date: Tue, 27 Oct 1998 22:21:11 PST > Reply-To: listproc(a)u.washington.edu > Sender: listproc(a)u.washington.edu > From: University of Washington ListProcessor <listproc(a)u.washington.edu> > To: bill_r(a)inetnebr.com > Subject: UNSUBSCRIBE CLASSICCMP > X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN > X-UIDL: ee07c31fcdb321395d34af85335a15b0 > > Dear user, > > your request > > UNSUBSCRIBE CLASSICCMP > > has been successfully processed. > > You have been removed from list CLASSICCMP (classiccmp(a)u.washington.edu). > Thank you for being with us. > > > > Bill Richman > incolor.inetnebr.com/bill_r > (Home of the COSMAC Elf > microcomputer simulator!) >

27 years, 10 months

FS: Assembly Language on 360/370 book

by tomowad＠earthlink.net

I was considering keeping this, but I came to the realization it is incredibly unlikely I'll ever have the desire to learn assembly on the 360. :-) Assembly Language Fundamentals 360/370, OS/VS, DOS/VS by Rina & Joshua Yarmish 768 pages, hardback $5 shipped. Tom Owad -- Sysop of Caesarville Online Client software at: <http://home.earthlink.net/~tomowad/>

27 years, 10 months

64bit data 128Bit address...Re: Building a Z-80 (64bit!

by allisonp＠world.std.com

< Address bus should be as wide as you think you might need plus a bit mor < As Allison said (again! Why oh why did I delete her post?) you want you < processor to be able to think about huge memories even if you can't buil < them and have to swap to disk. Actually the addres bus can be smaller than register size. For example we could build an 80 bit machine with 60bit address busses. The 60 bits is more than enough to address most likely memory needs for a long while yet if you need to do address math or other math 80bit long registers may make it much easier. The datapath bus can be any size as well but larger is generally better. The assumption of symetry is likely the most false. Allison

27 years, 10 months

Microvaxen bits etc.

by geoffrob＠stmarks.pp.catholic.edu.au

-----Original Message----- From: Tony Duell <ard(a)p850ug1.demon.co.uk> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, 28 October 1998 14:19 Subject: Re: Microvaxen bits etc. >Oh well... Another useful product becomes unavailable thanks to progress... > Seems that way. I may have found a source of new ones, but the price is a bit much. S/H ones seem to disappear as soon as they come out of service. >> Most network cards produced these days don't have AUI ports on them. >Yes, a lot of them are 10 base T only. Even though (IMHO) 10 base 2 makes >more sense for a small home network (no need to have a hub) and BNC plugs >are a lot easier to wire than those RJ45 things. Oh, RJ45's are no problem provided you have a decent tool. I use crimp on BNC's as well. I have a mix of both on my home network and at my shop. The school is all cat 5 now. >Fortunately, I got a load of transceivers at a radio rally with minor >faults (mostly open-circuit connections on the BNC connector). Lucky boy. >If there's a 16 pin chip near the BNC connector marked 83C92 or something >like that, then it can be made into a transceiver. You can either raid >the bits off the card or (Hey, a good idea...): >A lot of cards have 6 links that you have to move to select between AUI >and 10 base 2. They simply link the appropriate signals from the logic on >the card either to the AUI connector or to the internal transceiver. It >should be possible to feed signal from an AUI 'input' to the right pins >on those links, apply power (you probably only need the +12V line) to the >card and avoid a lot of work. <GRIN> Actually, this thought also crossed my mind whilst gazing at just such a card. I'm going to try that. I have an NE2000 clone card I'm going to try and convert to a txcvr. I think it needs +-12v and +- 5v, but that's not a big problem. (Diskless workstation PSU) >If you want to try this, then you'll need to trace out the schematic >around the links. It's worth knowing that most of the pulse transformers >used to isolate the logic signals at the transceiver contain 3 little >transformers in a 16 pin DIL package on pins (1,2,15,16), (5,6,12,13), >(7,8,9,10). Yep, can see them. >Trace the secondaries to the transceiver chip and then you >know what each transformer section is for (one will be Tx Data, one >RxData, one Collision). Alternatively, trace the link connections to the >ethernet chip on the card, but it may be more difficult to get data on >that. Not even gonna try. A direct patch into the txcvr from the AUI port with a little xover cabling ought to do it. > Did I mention that you'll need the data sheets on the transceiver chip? You did. Know a source? Online one preferably? >The pinout is : <snip> Got it, thanks for that. >> connect them. > >The cable is special :-(. It's 4 twisted pairs + shields (which you link >to the ground pins). One of the twisted pairs is thicker than the other >3, and is used for power. I imagine most anything will probably work, provided the leads are kept short. I have some shielded audio stuff that should do nicely. Something to experiment and tinker with for a while. :^) Cheers Geoff Roberts Computer Systems Manager Saint Marks College Port Pirie South Australia. My ICQ# is 1970476 Ph. 61-411-623-978 (Mobile) 61-8-8633-0619 (Home) 61-8-8633-8834 (Work-Direct) 61-8-8633-0104 (Fax)

27 years, 10 months

64bit data 128Bit address...Re: Building a Z-80 (64bit!

by Philip.Belben＠pgen.com

Hans Franke wrote: >>>> I therefore see address buses growing at 16 bits every 30 years. That's >>>> just over a bit every 2 years - slower than I expected but not much. >>>> Someone (I forget who) said that memory chips double in capacity every >>>> 18 months. This would give 16 bits in 24 years. > >>> Interesting szenario, especialy when connected to the Mores Law >>> (didn't he tell this regarding integration ?). > >> Thanks. That's the one I'm thinking of - the amount of memory you get on >> the same area of silicon doubles every 18 months. > > Basicly I think its about integrations and transistor > equivalents, but this is just linear to the size of memorys. > > In fact, to come back to the original question, Arfon > just took doubling of address space and doubbling of > data bus width for the same thing, but in fact they > are two different functions - widening data bus is > linear, while widening address bus is to the square > (sorry, my mathematical english just stops here). > This means doubble the data bus just doubbles the > date transfer rate (the only thing the data bus is > needed for) or w'=w+w. But doubbling the address bus > is putting the address range (and thats what the > address bus is for) to the square or r'=r*r. > > So, while a 256 or 512 bit data bus is usefull (and > already in use in main frames - only called data path), > even a 128 Bit address bus is just nonsense. Hmm. "Square" isn't the best way of putting it. In English we generally call that an "exponential" or "power" function: for an address bus of n bits the size of the memory is 2^^n words (pronounced "two to the power of n"). That's what I was getting at in my post. I agree totally that data paths should be as wide as possible. It wasn't just vaxen (Good post, Allison. A lot of very good points that I hadn't thought of) and mainframes that did that - the PERQ was a 16 or 20 bit machine but the memory data path was 64 bits wide (Help! Tony, you know more about this!) and fetched 4 words at a time for the processor to chew on, then 4 words for the video, 4 words for the I/O etc. Huge increase in speed. Address bus should be as wide as you think you might need plus a bit more. As Allison said (again! Why oh why did I delete her post?) you want your processor to be able to think about huge memories even if you can't build them and have to swap to disk. Philip.

27 years, 10 months

A Proposal (was - Re: Noise levels increasing and....)

by franke＠sbs.de

>> What's the point in proposing another list? If you want to try the >> experiment, build it. Make it happen. > Read the proposal. It isn't strictly a separate list. It is a list > connected by a one-way umbilical cord to the current list. It can't be > done by just creating another list. It has to be done on the current > server. Whether the list software is malleable enough to be shaped to the > task, I do not know. I am leaving it to others to comment on the > technical issue. The idea is to experiment and create a parallel flood > channel for certain things that run hot for a couple of weeks but are not > completely on topic. I don't think this is a "bozo" idea, and I hope you > will ponder its implications for more than a few minutes. I belive your idea could still be done on a second server. For your proposed testrun, a real check about the members of ClassicCmp to allow access for the sidebar list is not needed. The listserver will only be made public thru this list, so any subscription from outside is kind of uncommon. And even if there are some few, they shouldn't change the result in a real way. If the idea is right, an add on for the 'real' server might be made. Or we keep the second and just exchange the member list every other week to check the data base and we get another foot to stay on. Merging both lists into one folder should be no problem for any mail client out there (also splitting it up again into several theme folders). Gruss Hans P.S.: No, Steve, no comment on the subject, it's just a technical response. -- Ich denke, also bin ich, also gut HRK

27 years, 10 months

Doug and the Zuses (was:Re: KEITH, WE HARDLY KNEW YOU w

by franke＠sbs.de

>> Oh, did they pull of the DDR 1 Meg chip from display ? >> I belive this is the most funny Display _and_ a thing >> to think about with its implications. > They still had that display, but I don't remember falling over due to its > implications. Maybe the sign was in (East) German. What did I miss? (A > museum of eastern european technology would be pretty cool.) I might be proved wrong, but I belive this chip had a vital role to turn down the wall. In 1985 the Eastern German government decided that they had to pull up with a 1 Meg chip to show that their system is able to do all the same fine things than the west, all of us might temember that the 1 Meg thing was kind of journalists pussy when talking about the future back then. They already cloned the 80286. For the next years they poured all resources within electronic and process development into this project. It was almost like the idea of building a a PDP-8 >from scratch that has been around :) Of course, they already had a technology to produce 64k and prototype 256k, but without any help from outside it's kind of uncomfortable. Short before the wall came down, they finished, but at what cost: the whole development was sucked up into this single project - anything els was almost like stopped even production of actual components suffered. So this project added a lot to the economoc problems witch eventualy lead to the end of their system You know - people without video games and home computers tend to think about dangerous things (<g>). I'm not telling that this development has been the mayor reason, but it added stress to an already stressed system. Gruss Hans P.S.: There are only parts of the Z23 on display in Bonn - basicly only the drumm and drumm controll (AFAIR) -- Ich denke, also bin ich, also gut HRK

27 years, 10 months

Noise levels increasing and have become deafening

by franke＠sbs.de

>>> even breaking the lists in two - on and off topic >>> so that ppl with common interests can also talk about other things (like >>> experiences) >>> both lists would die though > I actually had a similar thought and it could work. Is it > possible to create an off-topic mailing list that is not publicly > advertised and cannot be subscribed to unless one were already a > subscriber to the on-topic one? Those that want the on-topic list > could get that, those who want both would get both and no one could > subscribe to only the off-topic one. The unwritten rule is that no new > topic could be spontaneously generated on the off-topic one and the > only new threads allowable would be those banished from the on-topic list. > Of course threads would be allowed to meander and mutate once they were > released to the off-topic list. This is just a thought. It certainly > would allow for these brief hot torrents of opinion on semi off-topic > material to run their course without inconveniencing those who wish to > only see hardcore tech info. The off-topic list would be like a sidebar > only accessible to those who read the on-topic one. Nice talk, but just think how hard it seams to be just to change the Subject line at the right moment AND to get all participants into changing it - not to mention the time delay. This is just an international thing - when I get up and have a first look at it Allison is still sleeping, Uncle Roger (or the other US West Coast guys) are just about to find their sleeping position, while Olminkhof is right about to leave the office - I've seen these things from other lists and news groups. It is just impossible. It is even impossible to live such a policy within a worldwide collaboration tool for a project. Even when corporate and special rules try to enforce it. And Moderation is just the dead of any list (maybe beside a anouncement list for 0190 (1-900) services, where they don't need any spontanous answer. >> This is not IRC, it is a mailing list. There is no need to use the >> silly little abbreviations designed to "speed up" on-line chat and >> the typing of same. Use English or as close an approximation as you >> can. Capital letters help as well as punctuation -- a carriage return Thank you. I hope I'm not hurting your eyes to hard. Fact is that some abbrevation like SCNR or AFAIK/R are thruout usefull, and fixed, so they can be used like IBM or VAX. But, I also dislike this ur2slw4me stuff - I need twice the to read it than regular. > Hey---just kidding around!! There are times this list > seriously lacks any sense of humor. It is ? I found some real good ones in the list :) Gruss H. P.S.: and for NINE mails in one day - I prefer to answer or comment directly, just to keep it small (ok, ok, I know I tend to elaborate whole bibles if I like something) and simple. Writing a mail composing several themes - what should it be named ? - where should it link ? And who will read it ? Just beside from the problem I would have to use additional word processing tools to combine it with the impossibility to keep an overview - I still have to do some regular job in my spare time. P.P.S.: Satisfied ? -- Ich denke, also bin ich, also gut HRK

27 years, 10 months

Classiccmp Friendly Pinout Page Update/Request

by aaron＠wfi-inc.com

Ok, I've gotten most of my stash transcribed into text documents on the site. The exception is the bus section, which contains a list of those pinouts that I have but am still working on. Anyway, what this really is is a request to people to dig through their piles of old docs and add some pinouts that aren't there yet. Tony Duell has offered to do PERQ machines, and anyone is welcome to contribute anything that's not there already. I put a file in the "pinouts" directory named "contributors.txt" which contains specific info about who is working on what. Please respond to me privately about this. URL: http://www.prinsol.com/classiccmp/ Aaron C. Finney Systems Administrator WFI Incorporated ------------------------------------------------------------------------ "UNIX is an exponential algorithm with a seductively small constant." --> Scott Draves

27 years, 10 months

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