I'm forwarding this message from another classic computer list I'm
on.... I figured you folks may be able to help him out a little
more. Please reply to him personally at his e-mail address given at
the far bottom....
Thanks,
CORD
--
I finally took a good look at that new PDP-11/23 I purchased some time
ago. It seems to have some normal looking DEC cards in it (LSI-11/2,
others). It does, however, have an interesting looking card set from
Associated Computer Consultants, called "MDMA" (as far as I can tell). It
appears to be from the mid-1980s. One card contains some sort of engine,
with ROMs and (4) 2901s. The other card contains a bunch of glue and
interface stuff, and has a connection to a big round military type
connector (the modern versions of the Cannon connector) on the back panel
of the chassis marked "IMP".
Being that this computer came from a certain spooky branch of the
U.S., that "IMP" looks awfully suspicious. Could this little DEC box have
been slated for the ARPAnet, but came just a little too late?
All I have is the processor - no drives or OS, so I can not tell much if I
power it up.
William Donzelli
william(a)ans.net
< I'm surprised by this. I'd thought about ways of linking any number
< of old PCs at up to 2000 foot distances, and thought about recreating a
2000ft is within the capability of RS422 at data rates that are in the
megabit range. There are other simple solutions like RS423 at low data
rates. The DEC mill used to have many central systems that often were
remote from the users by as many as 6 floors vertically and several
hundred feet horizontally. (Royalt was ML11/M1 and our group was
ML3-6/A1) we still ran 4800 or 9600 serial over the 500+ feet of wire
of the standard dual twisted pairs of phone co wire.
The biggest problem was the possibility of ground loops. With care
that's can be avoided though RS422 (balanced differential) can deal with
that as can RS485.
Allison
I have 2 of these XT bus boards, plus a PC-68K MMIO daughterboard.
They are copyright 1985/1986 by N.J. Costanzo & TLM Systems, Inc.
1-meg on-board, smartwatch, no cpu or roms
Can anyone provide additional information re:
original use, availability of roms, system software?
Any information appreciated.
Jim
< > You don't cut it you grind it! If done on a lathe you turn the rubbe
< > part and run a high speed grinder against it. It's insures it will b
< > concentric and gives a smooth surface.
<
< In the workshops I've seen where it's handled, it's usually done with a
< very sharp tool with a very acute cutting angle (I've seen razor blades
< mounted in a holder for this) and lubricated with glycerine.
You can if you have the right tools. Grinding is easier for most to do.
I make TU58 drive wheels using thickwall rubber tube or tygon and mount
the assembled result on an old tu58 motor and "grind" on a bench grinder.
I get a good round smooth surface, minimal setup. The hub used is the
one with the tire turned to goo, with the goo removed.
< For some jobs, I've seen a tubular cutter (rather like a cork borer)
< mounted in the tailstock and pressed into the workpiece, similarly
< lubricated with glycerine.
For general shapes its ok, the deformation affects accuracy. We used
that to get the general shape (tubes or plugs) and then mounted them
and did final grind. It was what the chief engineer wanted.
Generally the size of the drive roller is allowed considerable latitude
but roundness is desirable.
Allison
William Donzelli <william(a)ans.net> wrote:
> Lots of the stuff I have seen allows a user to insert an external clock -
> this can be handy for testing in the real world. Providing the clock is no
> big deal. Sure, it would be nice to get a dead-on clock for a T1, but as
> long as you keep the circuit private, the clock can be fairly sloppy.
Thanks for jogging my memory about that, I guess I've been in denial
about this stuff for a while. Yeah, if you're just running over a direct
cable (which is what I was thinking about) you'd be OK doing this.
> > Can you do this over dry copper, for short runs?
>
> Yes, some people on this list get connected this way (T1s that run a whole
> 20 feet, CSU to CSU, with no frame in between). A horrible kludge in a
> production environment, in my opinion, but it worked for quite a few
> years. Recently someone at ANS suggested that we use a T3 the same way,
> but he ended up being tarred and feathered.
Umm...why were you doing this? I can understand it for testing and as
a crude but expensive bandwidth limiter.
> > If so, would you want to? You mentioned in another post that you'd
> > have to run conduit for FDDI, and that makes me think there might be
> > some open space between hither and yon. Sure, you could run copper,
> > but wouldn't electrical potential differences be a problem?
>
> Differences as in losses due to the long run? That is what the Line Build
> Out option is for (on most CSUs). T1s, with thier twisted pair,
> differential design, tend to be pretty tough.
No, I was thinking about differences in ground potential between the
two buildings, static electricity, lightning strikes, that sort of
thing. All the canonical reasons why you wouldn't want to pull
Ethernet coax through that conduit.
-Frank McConnell
On Fri, 31 Jul 1998, I wrote
] Okay, I've now given up hope that those old modems will ever be
] at all useful or interesting to me. So they're up for grabs,
] for the cost of postage.
] ...blah, blah, blah...
To which there were several replies...
......................................................................
Tim Shoppa <shoppa(a)alph02.triumf.ca> wrote:
] > ... The consensus seems to be that they need some associated
] > equipment to do the dialing.
]
] The "associated equipment" is nothing more than a regular phone.
] ...
Can you tell me how to do that? An earlier reply (from Bill Pechter?)
said I needed a "dataphone", and would dial with that and then press
a "data" switch. I have neither a dataphone nor a data switch...
I did try mucking around with the "talk" switch and an ordinary telephone,
but couldn't get any interesting behavior out of them. (Ie: I connected
the "telco" socket on the modem to the phone line from the wall, and
then the telephone into "telset" on the modem. I also tried connecting
both the modem and the telephone to the wall via a "Y" adapter. Did I
miss some obvious thing? I don't now remember which setup gave what
results, but in the cases when I could actually dial out and get a
carrier, I couldn't get the modem to do anything about it.)
......................................................................
Russ Blakeman <rhblake(a)bbtel.com> wrote:
] > ... None respond to the Hayes "AT" command set, and each has a ...
] have you tried thr Racal Vadic command set, and do they have to be AT
] command compatible? I have a box stashed out in the storage building with
] a bunch of old modems, 300/1200/2400 types and all externals. I'll have
] to dig fo them this weekend (along with the Commie stuff I was supposed
] to get last weekend) and see what there is and let you know. What exactly
] are you planing to do with the modems and what speed do you need?
I've never even heard of the Racal Vadic command set, although I do
recognize the name as an old modem manufacturer. Hints would be welcome.
I don't have any real need for these modems, except that they are old
computer stuff, and were on their way to a land fill. I snagged 'em
mainly thinking that somebody on this list might be interested in them.
I could easily picture them on a shelf next to a Vax, happily chugging
away. (And for that purpose, I might hang onto one of them for myself.
But that leaves three taking up floor space.)
] > Similarly, I've got a Sytek 2532 Packet Communications Unit, with...
] Almost sounds like a multiplexer unit.....someone has a boat without an
] anchor out there.
:-)
Well, one man's anchor is another man's treasure, right? We aren't
hanging around on this list because we only like the fastest compustuff.
Anybody with a basement full of old computers might very well want some
old networking stuff to glue them together with.
As for me, I don't even have a basement. But I am off to a good start;
I have stuff to populate one.
......................................................................
Jack Peacock <peacock(a)simconv.com> wrote:
] Bill Yakowenko wrote:
] > There are two BellSouth 212A's, and two similar modems by Penril.
] From my experience with Penril modem the best thing you can do is send
] them to the dumpster. ...
What, no warm fuzzy nostagic feelings for these? :-)
How about this, slap a 56K modem inside the shell, maybe even wire up
the front-panel LEDs appropriately, and amaze your friends. It all
depends on what kind of thrill you're after.
......................................................................
BTW, if I come across more junk like this, should I continue to post
it here, or should I just list it on that web page and assume that
interested parties will find it?
Cheers,
Bill.
Okay, I've now given up hope that those old modems will ever be
at all useful or interesting to me. So they're up for grabs,
for the cost of postage.
There are two BellSouth 212A's, and two similar modems by Penril.
None respond to the Hayes "AT" command set, and each has a handful
of pushbutton switches on the front, as per my previous post.
Power supplies are all internal; they each have an ordinary 120v
line cord. The consensus seems to be that they need some associated
equipment to do the dialing. Because of this, I have no idea if
they work or not. They are each maybe 1' x 1' x 2", but not very
heavy. (That size is an estimate from memory, and might be off by
a bit).
I doubt they are useful in any modern setup, but they might be
regarded as classics. If nobody here wants them, they return to
the dumpster from which they came. My apartment now has negative
space available, if you know what I mean.
Similarly, I've got a Sytek 2532 Packet Communications Unit, with
about half a dozen boards in it. This is a rack-mount beastie, and
weighs like it, so it could be expensive to ship. Still, if you
want it, or any of the boards from it, let me know. Like the modems,
I have no way to test it, and no idea whether or not it works. But
I'd be thrilled to get it out of the trunk of my car. :-)
And maybe this is a good time to mention my "for trade" web page,
containing a list of compu-junk that needs a good home. It is at
this URL: http://www.cs.unc.edu/~yakowenk/classiccmp/fortrade.html
Cheers,
Bill.
Since I rediscovered a B500 in my junk some weeks ago,
I'm searching for information. Until now i could trace
nothing in the web or any magazine from that time.
The Computer in question is a Commodore B500, Basicly
a CBM II LP. I am not talking about the P500. The mobo
is technicaly the same than the CBM 610 (B128) but a
different layout (only some lines) and a (lower) part#.
Also the Version/Part#'s of the kernal/basic EPROMS are
lower than any known (to me) B128/B256/6x0/7x0 type.
The mobo and all chips are dated to 1982 - again way
before any other CBM II I know. AFAIR the CBM II line
was introducted in 1983.
Any Info would be usefull.
Gruss
H.
--
Ich denke, also bin ich, also gut
HRK
I finally got back to working on my PDP-11/44, and finished cleaning it up
yesterday. So now I'm ready to start testing stuff.
Which brings me to my question, I went ahead and plugged the TU-58 drives
in to see if they would give any indication of life. Not a thing. Do they
have to be plugged into the line (serial I think), or have a tape in them
before they will show any signs of life?
Zane
| Zane H. Healy | UNIX Systems Adminstrator |
| healyzh(a)ix.netcom.com (primary) | Linux Enthusiast |
| healyzh(a)holonet.net (alternate) | Classic Computer Collector |
+----------------------------------+----------------------------+
| Empire of the Petal Throne and Traveller Role Playing, |
| and Zane's Computer Museum. |
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