><OK, how about it. Put a ring of compasses around the wire with needles str
><enough magnetised that they will stay pointing N-S around the ring regardle
><the Earth's field.
><
><Can you then flip them with a current? A very good visual demonstration of
><core works!
>
> Yep, That would be good to watch but that's really a demo of the fields
> around conductors (imporant building block).
I actually meant to take the demo one step further. Each compass needle has its
own magnetic field. Put them close enough together and (with luck) the N end of
one needle will attract the S end of the other.
Put several of these compases in a ring, and the needles will point around the
ring, whether or not there is a current flowing down a wire in the middle.
And there are two stable states, just like a core.
With (even more) luck, you can flip between states with a current. Just like
core.
Worth a try?
This weekend I shall see if I can find some cheap, small compasses in a toy shop
or somewhere...
Philip.
Ok, I booted a disk labelled "HT-11B distribution" on my H-11 and it comes
up to the "." prompt. But not much else. (dir doesn't work for example)
Is there a clue page somewhere ?
--Chuck
>had DCL incorporated in it... to get a directory, you have to
>run PIP (R PIP) and issue the command 'ddx:/L' where dd is the
>device you're using (presumably DX) and 'x' is the unit number.
Yep, ignore my comment about R DIR. I'm pretty sure that DIR.SAV
didn't exist until CCL came about (though of course you never know
for sure with HT-11...)
I spent an hour explaining to the folks at Mentec yesterday how
IGETC and IFREEC aren't in RT-11 V5.5 and later SYSLIB.OBJ, despite how
the manual said that they were still there :-).
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
>Ok, I booted a disk labelled "HT-11B distribution" on my H-11 and it
>comes up to the "." prompt. But not much else. (dir doesn't work for
example)
I believe HT-11 was based on a version of RT-11 which had not yet
had DCL incorporated in it... to get a directory, you have to
run PIP (R PIP) and issue the command 'ddx:/L' where dd is the
device you're using (presumably DX) and 'x' is the unit number.
Megan Gentry
Former RT-11 Developer
+--------------------------------+-------------------------------------+
| Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com |
| Unix Support Engineering Group | (home): mbg!world.std.com |
| Compaq Computer Corporation | addresses need '@' in place of '!' |
| 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ |
| Nashua, NH 03062 | "pdp-11 programmer - some assembler |
| (603) 884 1055 | required." - mbg |
+--------------------------------+-------------------------------------+
>Ok, I booted a disk labelled "HT-11B distribution" on my H-11 and it comes
>up to the "." prompt. But not much else. (dir doesn't work for example)
Try a "R DIR".
What is the exact text of the error message? (You know, the error
messages are not put there for you to ignore. They do mean something
to others, even if they seem cryptic to you.)
>Is there a clue page somewhere ?
I think your copy of HT-11B will be roughly equivalent to RT-11 V2
(maybe V3). No online help. You should find the big set of blue books
that came with it! Many of the utility options from later versions
of RT will work, but not all, and the details of a SYSGEN changed greatly
between major versions.
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
Doing a casual dumpster dive this eve and found a box with
Vic-1520 Colour Printer Plotter. NIB including manual and cables. Unopened
tube containing the 4 colour nibs. Dont know if they're dried out but they're
water-based.
An MJB H8401 4 socket game-port expander and 40/80 converter
in a really sturdy metal case with 6-led select switch and reset.
C= 802 printer like new.
New parallel card for Apple ll with cable and lle socket plus typed manual
>from PC Wares .
What looks to be a 1/2 ht. 5 1/4 Apple ll floppy in a 1541 case usual All
cable but with a different non-apple controller card inside ??
A Bantam paperback manual on the Timex-Sinclair 1000 and a couple of
copied mmanuals (Oxford Pascal for C64, Spinnaker), a package from Quantum
Link with a discount coupon. Wonder if AOL would honor it ? :^))
Made my day !
ciao larry
lwalker(a)interlog.com
Let us know of your upcoming computer events for our Events Page.
t3c(a)xoommail.com
Collectors List and info http://members.xoom.com/T3C
I agree in principle but I just double checked my memory and just looked at
my HT feed. It is only connected to the HT line and then drops down into a
conduit and under ground for the ~800 feet to the pedistal mounted
transformer. There is only the 1 connection at the pole. A friend of mine
used to burry lines for the local phone company and has hit on occasion
(when the locator screwed up) the 14KV drops and said all he ever finds is a
single wire from the result. He did say it is impressive when it gets
shorted however. He has melted teeth off the backhoe bucket and his ears
hurt for a while afterwords. It also works wonders on the ditch witch teeth
and the vibrating plow blades. Even though the power drops are supposed to
be a minimum of 3 feet down that is not always the case.
Dan
> I don't know about where you come from but in my state,
>the power company is required to keep the ground current to
>a minumum. The smallest power line I've see was two wires.
>Much of the older telegraph lines used ground return. I don't
>think it would be good for general power distribution. They also
>used ground return on many telephone setups.
> This reminds me of a story I once heard:
> A phone repairman heard of this dog that could predict
>when the phone would ring. A few seconds before the bell
>rang, the dog would let out a howl.
> He had to see this magic dog.
> He when to the old ladies house and he found the dog chained
>to the telephone box on the side of the house. He then realized
>how the dog knew. You see, it was winter and the ground was
>frozen at the box. This meant that when a ring came in, it
>didn't have enough current to make the bell ring but there
>was enough current to give the dog a strong shock through
>the chain. The poor dog would get a nasty shock and urinate
>on the ground. On the next ring, the urine would provide
>enough conduction that the bell would ring.
> That is the story of the magic dog.
>Dwight
>
>Dwight
>
>
>I've just gotta ask! Does it bring the worms to the surface when it
>rains?
> - don
I have never looked but I suppose it might. I have a 400A service and
sometimes I do a fair job of loading it. The transformer ped is out of the
way so I rarely go closer than 30 feet from it. They also must put the
ground rod(s) inside the for safety (hate to think what it would be like if
the ground got cut on the primary). I have never seen them but they have to
be there somewhere.
Dan
