27 Jun
2023
27 Jun
'23
6:16 p.m.
Anyone in MD got an AUI cable (few feet long) I can steal so I don't
have to remove the bolts from the Pro/380's Ethernet socket or the pins
on my 10bt ethernet MAU?
Friendly note: If you try to boot a Pro/380 running POS 3.2 with Decnet
installed and don't have the loopback plug the system will crash hard
with a numeric error on the display. Noted.
CZ
27 Jun
27 Jun
6:19 p.m.
Anyone in MD got an AUI cable (few feet long) I can
steal so I don't have to
remove the bolts from the Pro/380's Ethernet socket or the pins on my 10bt
ethernet MAU?
I just cheat and use a straight through DB-15 (waiting for someone to tell me
it's a DQ-15 or something instead ;), like a PC joystick cable or some such.
Friendly note: If you try to boot a Pro/380 running
POS 3.2 with Decnet
installed and don't have the loopback plug the system will crash hard with a
numeric error on the display. Noted.
Duly noted for the one I have here, but it runs Venix/PRO. Gotta try 2.9BSD one
of these days.
--
------------------------------------ personal: http://www.cameronkaiser.com/ --
Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser(a)floodgap.com
-- 1-GHz Pentium-III + Java + XSLT == 1-MHz 6502. -- Craig Bruce --------------
7:35 p.m.
On Tue, 27 Jun 2023, Cameron Kaiser via cctalk wrote:
Since you asked for it, the PC joystick connector was a DA-15;
the PC VGA connector was a DE-15.
A DB-9 was a 25 pin connector (often serial), and often with pins 1-8 and
20. I don't know which pins would be present on a DB-15.
Anyone in MD
got an AUI cable (few feet long) I can steal so I don't have to
remove the bolts from the Pro/380's Ethernet socket or the pins on my 10bt
ethernet MAU?
I just cheat and use a straight through DB-15 (waiting for someone to tell me
it's a DQ-15 or something instead ;), like a PC joystick cable or some such. 
9:52 p.m.
If we're being pedantic.... ;-)
On 6/27/23 9:35 PM, Fred Cisin wrote:
Since you asked for it, the PC joystick connector was
a DA-15;
the PC VGA connector was a DE-15.
Wasn't PC VGA considered a /High/ /Density/
DE-15?
A DB-9 was a 25 pin connector (often serial), and
often with pins 1-8
and 20. I don't know which pins would be present on a DB-15.
I'm not tracking. How is a DB-9 (pin) *cough* DE-9 *cough* a 9-pin
connector? How does that make it to the DB-25?
Or are you meaning to say that many DB-25 pin serial ports were really
wired up as if they were a 9-pin serial port, independent of the
physical connector?
DB-15??? Did you mean DA-15?
I'll see myself out now. ;-)
Grant. . . .
10:13 p.m.
If we're being pedantic.... ;-)
> Since you asked for it, the PC joystick connector was a DA-15;
> the PC VGA connector was a DE-15.
On Tue, 27 Jun 2023, Grant Taylor via cctalk wrote:
Wasn't PC VGA considered a /High/ /Density/
DE-15?
It is sometimes caalled that.
A DB-9 was a
25 pin connector (often serial), and often with pins
1-8 and 20. I don't know which pins would be present on a DB-15.
I'm not tracking. How is a DB-9 (pin) *cough* DE-9 *cough* a 9-pin
connector? How does that make it to the DB-25?
Or are you meaning to say that many DB-25 pin serial ports were really
wired up as if they were a 9-pin serial port, independent of the
physical connector?
DB-15??? Did you mean DA-15?
I'll see myself out now. ;-)
28 Jun
28 Jun
5:18 a.m.
On Jun 28, 2023, at 1:13 AM, Fred Cisin via cctalk
<cctalk(a)classiccmp.org> wrote:
DA, DC, DE connectors are a different size D shell than the DB, which is the one commonly
used for a 25 pin cable.
There is also DD, though I've never seen one in the wild. DA is the shell for AUI
connectors, DC is used for RS-422 (37 pins) I think.
All of these come in regular density and high density variations. For most of them,
regular is 2 rows and HD is 3 -- so a VGA connector is a DE-15, high density DE shell
connector. But the DD regular density is 3 rows and the high density is 4 rows.
Meanwhile, on AUI cables: the difficulty with plugging a transceiver into the Pro is that
the Pro uses regular nuts, for a plug that secures by screws. That's non-standard,
since the AUI spec calls for the "turret" and sliding latch type. So a standard
AUI cable wouldn't be a real cure because you'd still have that mismatch.
A simple solution is an adapter. I bought one from L-com:
https://www.l-com.com/d-sub-aui-to-db15-adapter-male-female which says that it is
"discontinued" but also shows "available: 11" so perhaps you can still
get one. Failing that, an option would be to get a "socket saver" -- which is
just a thin device with a connector at each end, intended to save the device connectors
from wear -- and remove the transceiver-side fastener so the transceiver can plug in.
That second option doesn't give you a secure attachment but it's likely good
enough.
paul
5:23 a.m.
Meanwhile, on AUI cables: the difficulty with plugging
a transceiver into the Pro is that the Pro uses regular nuts, for a plug that secures by
screws. That's non-standard, since the AUI spec calls for the "turret" and
sliding latch type. So a standard AUI cable wouldn't be a real cure because you'd
still have that mismatch.
Yup, it's a DEC thing, however the DEQNA cab kits do the proper cam and
lock interface. I thought about removing the nuts, but went with
ordering a cable and I'll pull the studs off it to make it work. Sub
optimal but that is DEC (also I remember AUI cables did come with screws
so other vendors did this in the early days as well)
Ordered from Ebay, all well. Next step is to start figuring out how to
VMR the POS.SYS file and see how the drivers are in there.
CZ
A simple solution is an adapter. I bought one from
L-com: https://www.l-com.com/d-sub-aui-to-db15-adapter-male-female which says that it is
"discontinued" but also shows "available: 11" so perhaps you can still
get one. Failing that, an option would be to get a "socket saver" -- which is
just a thin device with a connector at each end, intended to save the device connectors
from wear -- and remove the transceiver-side fastener so the transceiver can plug in.
That second option doesn't give you a secure attachment but it's likely good
enough.
paul
9:06 a.m.
On Wed, Jun 28, 2023 at 5:02 PM Chris Zach via cctalk
<cctalk(a)classiccmp.org> wrote:
Yup, it's a DEC thing, however the DEQNA cab kits
do the proper cam and
lock interface. I thought about removing the nuts, but went with
ordering a cable and I'll pull the studs off it to make it work. Sub
optimal but that is DEC (also I remember AUI cables did come with screws
so other vendors did this in the early days as well)
Classic PERQs certainly did (4-40 UNC jackposts and screws rather than
the slidelock). That's one reason I had to make my own AUI cable. Of
course a couple of weeks later I spotted a couple of cables with DA15
connectors being thrown out. I grabbed them, they turned out to be
genuine ICL PERQ AUI cables...
-tony
9:42 a.m.
On Jun 28, 2023, at 8:23 AM, Chris Zach via cctalk
<cctalk(a)classiccmp.org> wrote:
Yes, DEC usually did things per the standard, which makes sense since after all they wrote
a lot of it, but the Pro (and apparently a few other devices) did it strangely.
As for other vendors, I've heard that. The DEC case is so strange partly because of
DEC's tradition of following standards, and partly from the fact that with the Pro you
have a cable with one standard and one non-standard connector.
Did you look at the L-com adapter? That's the ideal answer, if you can still get one.
Or if some other vendor offers the same thing. I have one of those on my Pro, along with
a couple of "connector savers" to allow normal connectors to connect without
bumping into the plastic shell of the Pro.
paul
Meanwhile, on AUI cables: the difficulty with
plugging a transceiver into the Pro is that the Pro uses regular nuts, for a plug that
secures by screws. That's non-standard, since the AUI spec calls for the
"turret" and sliding latch type. So a standard AUI cable wouldn't be a real
cure because you'd still have that mismatch.
Yup, it's a DEC thing, however the DEQNA cab kits do the proper cam and lock
interface. I thought about removing the nuts, but went with ordering a cable and I'll
pull the studs off it to make it work. Sub optimal but that is DEC (also I remember AUI
cables did come with screws so other vendors did this in the early days as well) 
10:14 a.m.
On 6/28/2023 8:23 AM, Chris Zach via cctalk wrote:
Not necessarily a DEC thing. TEMPEST PC's (and other TEMPEST boxes like
fiber
ethernet transceivers) also had screw connectors rather than the spring
clip ones.
bill
Meanwhile, on AUI cables: the difficulty with
plugging a transceiver
into the Pro is that the Pro uses regular nuts, for a plug that
secures by screws. That's non-standard, since the AUI spec calls for
the "turret" and sliding latch type. So a standard AUI cable
wouldn't be a real cure because you'd still have that mismatch.
Yup, it's a DEC thing, however the DEQNA cab kits do the proper cam
and lock interface. I thought about removing the nuts, but went with
ordering a cable and I'll pull the studs off it to make it work. Sub
optimal but that is DEC (also I remember AUI cables did come with
screws so other vendors did this in the early days as well)
11:20 a.m.
Not necessarily a DEC thing. TEMPEST PC's (and
other TEMPEST boxes like
fiber
ethernet transceivers) also had screw connectors rather than the spring
clip ones.
It's semi-common on random old stuff, yeah. I've got a Cisco IGS that uses
jackscrews, and have had a pretty good number of ISA Ethernet boards that use either
jackscrews in the usual D-SUB location, or the really wide-set ones that like two
transceivers fit.
For the Cisco IGS, there's a part # for an adapter cable with jackscrews on the router
end and slide latches on the transceiver end, but they rarely show up. I have one or two
for it, but have not found more.
Protip: Ungermann-Bass made jackscrew transceivers both ways (wide and standard) and
they're usually cheap.
Thanks,
Jonathan
5:31 a.m.
I probably have one here in Landenberg which is on the PA side of the MD/PA
border if you can find no other sources. Not in front of me to verify, but
I think I have three plastic bins of them along with related parts.
Bill
On Wed, Jun 28, 2023, 8:19 AM Paul Koning via cctalk <cctalk(a)classiccmp.org>
wrote:
On Jun 28, 2023, at 1:13 AM, Fred Cisin via
cctalk <
cctalk(a)classiccmp.org> wrote:
DA, DC, DE connectors are a different size D shell than the DB, which is
the one commonly used for a 25 pin cable.
There is also DD, though I've never seen one in the wild. DA is the shell
for AUI connectors, DC is used for RS-422 (37 pins) I think.
All of these come in regular density and high density variations. For
most of them, regular is 2 rows and HD is 3 -- so a VGA connector is a
DE-15, high density DE shell connector. But the DD regular density is 3
rows and the high density is 4 rows.
Meanwhile, on AUI cables: the difficulty with plugging a transceiver into
the Pro is that the Pro uses regular nuts, for a plug that secures by
screws. That's non-standard, since the AUI spec calls for the "turret"
and
sliding latch type. So a standard AUI cable wouldn't be a real cure
because you'd still have that mismatch.
A simple solution is an adapter. I bought one from L-com:
https://www.l-com.com/d-sub-aui-to-db15-adapter-male-female which says
that it is "discontinued" but also shows "available: 11" so perhaps
you can
still get one. Failing that, an option would be to get a "socket saver" --
which is just a thin device with a connector at each end, intended to save
the device connectors from wear -- and remove the transceiver-side fastener
so the transceiver can plug in. That second option doesn't give you a
secure attachment but it's likely good enough.
paul
6:27 a.m.
On Wed, Jun 28, 2023 at 1:19 PM Paul Koning via cctalk
<cctalk(a)classiccmp.org> wrote:
The DD50 (standard density) has been used for SCSI-1 (maybe old Sun
machines?) amongst other places. I've certainly used them. I did once
fit an ST412 interface onto a DD50 socket. There's a total of 54 wires
on the 34 pin control and 20 pin data cables of course but enough
wires unused on the latter than you can get away with 50 pins.
I've seen a DD78 on some HP device but I forget what.
DC37 was used for RS449, PC external floppy drives,etc. DC62 was the
connector for the IBM5161 expansion unit.
There are DA26 and DB44 connectors but I don't think I've ever used them.
FWIW I have seen Centronics parallel interfaces on DA15 connectors
(there are enough pins for 8 data lines, strobe, busy, ground and a
few other signals). There is NO standardisation, I've got a Tandata
videotext terminal, a Philips videotext terminal and an HP2225P
printer here and they don't even agree on the ground and data lines.
-tony
On Jun 28, 2023, at 1:13 AM, Fred Cisin via
cctalk <cctalk(a)classiccmp.org> wrote:
DA, DC, DE connectors are a different size D shell than the DB, which is the one commonly
used for a 25 pin cable.
There is also DD, though I've never seen one in the wild. DA is the shell for AUI
connectors, DC is used for RS-422 (37 pins) I think. 
11:14 a.m.
50 pin DD connectors are alive and well on the backplanes of some day job ATRs with new
electronics in the old VME form factor. 3 x 16 STPs pass through them very nicely en
route to front panel connectors. Both dense, decently robust and legacy compliant.
More generally, if you have access to a Daniels AFM8 crimp tool and positioner, the
Harting crimp contact Dsubs are very good for odd jobs; e.g.
https://uk.rs-online.com/web/p/d-sub-connectors/1007759 The turned pin contacts are much
preferable to the bent tin ones e.g.
https://www.peigenesis.com/en/shop/part-information/M3902964369/TRI/EACH/30…
Unfortunately, while the bodies are inexpensive the pins and infrastructure are not. More
positively, the connectors don't noticeably degrade with rework.
Martin
-----Original Message-----
From: Paul Koning via cctalk [mailto:cctalk@classiccmp.org]
Sent: 28 June 2023 13:19
To: cctalk(a)classiccmp.org
Cc: Paul Koning <paulkoning(a)comcast.net>
Subject: [cctalk] Re: Need AUI cable
On Jun 28, 2023, at 1:13 AM, Fred Cisin via cctalk
<cctalk(a)classiccmp.org> wrote:
DA, DC, DE connectors are a different size D shell than the DB, which is the one commonly
used for a 25 pin cable.
There is also DD, though I've never seen one in the wild. DA is the shell for AUI
connectors, DC is used for RS-422 (37 pins) I think.
All of these come in regular density and high density variations. For most of them,
regular is 2 rows and HD is 3 -- so a VGA connector is a DE-15, high density DE shell
connector. But the DD regular density is 3 rows and the high density is 4 rows.
Meanwhile, on AUI cables: the difficulty with plugging a transceiver into the Pro is that
the Pro uses regular nuts, for a plug that secures by screws. That's non-standard,
since the AUI spec calls for the "turret" and sliding latch type. So a standard
AUI cable wouldn't be a real cure because you'd still have that mismatch.
A simple solution is an adapter. I bought one from L-com:
https://www.l-com.com/d-sub-aui-to-db15-adapter-male-female which says that it is
"discontinued" but also shows "available: 11" so perhaps you can still
get one. Failing that, an option would be to get a "socket saver" -- which is
just a thin device with a connector at each end, intended to save the device connectors
from wear -- and remove the transceiver-side fastener so the transceiver can plug in.
That second option doesn't give you a secure attachment but it's likely good
enough.
paul
6:29 a.m.
On Wed, Jun 28, 2023 at 6:13 AM Fred Cisin via cctalk
<cctalk(a)classiccmp.org> wrote:
With many boxes of used cables, often there will be
cables that are DB-25,
but with 16 pins missing in the 25 pin connector, often leaving pins 1-8
and 20, and gaps where other pins could have been.. I call THAT a DB-9
The DE9 serial port includes RingIndicator (pin 22 on the DB25 one)
but not protective ground (pin 1 of the DB25). I've found a number of
cables that therefore wire 10 pins -- 1-8,20,22. You can call that a
DB10 if you like (I don't)
-tony
1:09 p.m.
On 6/28/23 12:13 AM, Fred Cisin wrote:
It is sometimes caalled that.
;-)
With many boxes of used cables, often there will be
cables that are
DB-25, but with 16 pins missing in the 25 pin connector, often leaving
pins 1-8 and 20, and gaps where other pins could have been.. I call
THAT a DB-9 :-) Similarly, if a DB-25 has 10 pins missing from the 25
pin connector, then I call THAT a DB-15.
That's ... different than I would have expected.
I can see the logic. But I don't think I would have gotten there on my
own without seeing / reading examples.
DA, DC, DE connectors are a different size D shell
than the DB, which is
the one commonly used for a 25 pin cable.
ACK
27 Jun
27 Jun
6:37 p.m.
These are my go-to for short ones:
https://www.ebay.com/itm/233295839501
Not affiliated with seller, just a satisfied customer.
Thanks,
Jonathan
------- Original Message -------
On Tuesday, June 27th, 2023 at 21:16, Chris Zach via cctalk <cctalk(a)classiccmp.org>
wrote:
Anyone in MD got an AUI cable (few feet long) I can steal so I don't
have to remove the bolts from the Pro/380's Ethernet socket or the pins
on my 10bt ethernet MAU?
Friendly note: If you try to boot a Pro/380 running POS 3.2 with Decnet
installed and don't have the loopback plug the system will crash hard
with a numeric error on the display. Noted.
CZ
8:26 p.m.
On Wed, Jun 28, 2023 at 2:17 AM Chris Zach via cctalk
<cctalk(a)classiccmp.org> wrote:
Anyone in MD got an AUI cable (few feet long) I can steal so I don't
have to remove the bolts from the Pro/380's Ethernet socket or the pins
on my 10bt ethernet MAU?
For a few inches, which would be enough here I think, I've used an IDC
DA15 plug and socket crimped onto the normal ribbon cable. Technically
it's wrong but the reflections on that length of cable won't matter.
-tony
10 p.m.
Tony's email makes me ask more questions than I have (smart alack)
answers to. Maybe ~> hopefully I can ~> will learn something.
On 6/27/23 10:26 PM, Tony Duell wrote:
For a few inches, which would be enough here I think,
I've used an IDC
DA15 plug and socket crimped onto the normal ribbon cable. Technically
it's wrong but the reflections on that length of cable won't matter.
Isn't 10Base<something> quite resilient? Especially at these distances?
Though I don't know if AUI is considered 10Base<anything> in and of
itself. Doesn't it become 10Base5 / 10Base2 / 10Base-T based on what
transceiver is on the other side of / attached to the other end of the
AUI cable?
I'm assuming that MAU is meant for multiple stations to connect an AUI
cable into and it then connects to the ostensibly 10Base<something>
network. -- I originally read and was replying as if Chris was trying
to take the AUI port on his Pro/380 and connect it to an AUI port on a
hub / switch. My concern being that both AUI ports would be the same
gender and assuming that there are (at least) a pair of transceivers
converting each device from AUI to 10Base<something> to connect to each
other.
Grant. . . .
28 Jun
28 Jun
5:23 a.m.
On Jun 28, 2023, at 1:00 AM, Grant Taylor via cctalk
<cctalk(a)classiccmp.org> wrote:
Tony's email makes me ask more questions than I have (smart alack) answers to. Maybe
~> hopefully I can ~> will learn something.
On 6/27/23 10:26 PM, Tony Duell wrote:
Very definitely. The Ethernet spec gives a 50 meter limit for the AUI cable length, and
describes it as a controlled impedance cable with shielded twisted pairs. But I agree
with Tony that for short lengths a plain ribbon cable would do just fine. And
"short" I would define as "electrically short" -- much less than a
wavelength, so one meter is likely still ok if you need that much.
For a few inches, which would be enough here I
think, I've used an IDC DA15 plug and socket crimped onto the normal ribbon cable.
Technically it's wrong but the reflections on that length of cable won't matter.
Isn't 10Base<something> quite resilient? Especially at these distances? Though I don't know if AUI is considered
10Base<anything> in and of itself. Doesn't it become 10Base5 / 10Base2 /
10Base-T based on what transceiver is on the other side of / attached to the other end of
the AUI cable?
Correct. The AUI cable is defined for 10 Mb/s Ethernet, and the transceiver at the far
end attaches it to 10Base5 or 2 or T or even "broad" (Ethernet over cable TV).
paul
6:48 a.m.
On Wed, Jun 28, 2023 at 6:00 AM Grant Taylor via cctalk
<cctalk(a)classiccmp.org> wrote:
Tony's email makes me ask more questions than I have (smart alack)
answers to. Maybe ~> hopefully I can ~> will learn something.
I was being a bit of a smart alec too. The point I was making is that
a bit of normal IDC ribbon cable is not electrically the correct cable
for an AUI interface but it won't matter over a few inches.
The correct cable is 4 twisted pairs with a overall screen (shield).
One pair is thicker wires than the other 3 and is used for the power.
This cable was very hard to get by the metre when I needed some about
30 years ago, and a full reel was several hundred pounds. I was lucky
enough to be given a couple of metres as an 'offcut' by a gentleman
who worked in network support. You probably need something like that
if you're makng a 1m cable. But not for what the OP is trying to do.
On 6/27/23 10:26 PM, Tony Duell wrote:
There are 2 problems with the wrong cable. Firstly will it carry the
current for the power supply pins? My experience is that it will, at
least for most transceivers.
The second is that the characteristic impedance is wrong. It's
actually not too far off but... This will cause reflections. It won't
matter on a few inches as the reflections will take about a nanosecond
to get back and will die out in << the bit time. It may matter on
longer cables.
For a few inches, which would be enough here I
think, I've used an IDC
DA15 plug and socket crimped onto the normal ribbon cable. Technically
it's wrong but the reflections on that length of cable won't matter.
Isn't 10Base<something> quite resilient? Especially at these distances?
Though I don't know if AUI is considered 10Base<anything> in and of
itself. Doesn't it become 10Base5 / 10Base2 / 10Base-T based on what
transceiver is on the other side of / attached to the other end of the
AUI cable?
AFAK AUI is not 10baseAnything for the reason you give
I'm assuming that MAU is meant for multiple stations to connect an AUI
MAU is something like 'media access unit' and is the official name for
a transceiver. Due to the fact that there had to be a certain distance
between transceivers on the cable, there were things that had multiple
AUI connectors to link to computers (these were normally male DA15s on
the unit, so a normal transceiver cable would work) and a further AUI
connector (normally a female DA15) for a transceiver onto the 'real'
ethernet. DEC's DELNI is a common-ish example of such a unit, I think
the printset is on bitsavers
cable into and it then connects to the ostensibly
10Base<something>
network. -- I originally read and was replying as if Chris was trying
to take the AUI port on his Pro/380 and connect it to an AUI port on a
hub / switch. My concern being that both AUI ports would be the same
gender and assuming that there are (at least) a pair of transceivers
converting each device from AUI to 10Base<something> to connect to each
other.
There is no real equivalent of an 'AUI null modem cable' (should that
be 'null transceiver cable'?)
If you want to link 2 computer-type ports together you need the
equiavelent of 2 transceivers. Probably the easiest is a pair of
10baseT transceivers and a crossover 8p8c cable
If you want to link 2 transceivers together on the AUI side then
that's a network bridge. Even a basc one is quite a lot of
electronics. If you want it to only pass on packets for particular
machines then it gets very complicated, one that I picked up last year
contains a 68020 CPU _and_ a board containing a 16 bit processor made
from 2900-series bitslice stuff
-tony
6:56 a.m.
There is no real equivalent of an 'AUI null modem
cable' (should that
be 'null transceiver cable'?)
If you want to link 2 computer-type ports together you need the
equiavelent of 2 transceivers.
This (or devices like it) is probably the only single-piece two station "null modem
adapter":
https://i.imgur.com/qiMh9Tc.jpg
It's a twin tap, with two AUI connectors. If you drop an intrusive BNC or N tap in
there and terminate it, it'd act like a "null modem" for AUI.
If you want to link 2 transceivers together on the AUI
side then
that's a network bridge. Even a basc one is quite a lot of
electronics.
DEC's full wirespeed bridge was supposedly considered something of an engineering
miracle at the time and occupies 2U of rack space!
Thanks,
Jonathan
7:36 a.m.
On Jun 28, 2023, at 9:56 AM, Jonathan Chapman via
cctalk <cctalk(a)classiccmp.org> wrote:
...
3U. But yes, it took some pretty good wizardry to run at that speed with the machinery of
the time, certainly at that cost. Along the same lines, designing the DECbridge-900 was
quite an interesting exercise. While it doesn't run quite at 6 x Ethernet wire speed,
it does manage about 60k packets per second. More importantly, it includes algorithms to
ensure that spanning tree packets are always handled even if the device is presented with
an overload. You can see it in US patent 6,301,224. The DECbridge-900 achieved that
performance with forwarding in software, in a Motorola 68040 at 25 MHz, with a little help
from a 64-entry CAM.
For wiring two 10Mb Ethernet NICs together, a bridge will certainly serve, as will a pair
of transceivers. A repeater will also do the job. Or a DELNI, which isn't
technically a repeater; I don't think it is a device described by the standard at all,
just a piece of magic that interoperates with the standard by suitable magic.
paul
If you want to link 2 transceivers together on
the AUI side then
that's a network bridge. Even a basc one is quite a lot of
electronics.
DEC's full wirespeed bridge was supposedly considered something of an engineering
miracle at the time and occupies 2U of rack space!
7:40 a.m.
On Jun 28, 2023, at 9:48 AM, Tony Duell via cctalk
<cctalk(a)classiccmp.org> wrote:
On Wed, Jun 28, 2023 at 6:00 AM Grant Taylor via cctalk
<cctalk(a)classiccmp.org> wrote:
Not for one meter. For 50 meters, sure, although a piece of Cat 5 Ethernet cable for the
signals along with a separate wire pair for power may well be an entirely adequate
substitute. The rule of thumb I would use is that any wrong-impedance connection shorter
than a 5 percent or so of the wavelength isn't a problem. For 10 Mb/s Ethernet that
translates to 1.5 to 2 meters.
This is also why "UHF" connectors are acceptable at RF frequencies (but not at
UHF frequencies, never mind what they call themselves).
paul
Tony's email makes me ask more questions than I have (smart alack)
answers to. Maybe ~> hopefully I can ~> will learn something.
I was being a bit of a smart alec too. The point I was making is that
a bit of normal IDC ribbon cable is not electrically the correct cable
for an AUI interface but it won't matter over a few inches.
The correct cable is 4 twisted pairs with a overall screen (shield).
One pair is thicker wires than the other 3 and is used for the power.
This cable was very hard to get by the metre when I needed some about
30 years ago, and a full reel was several hundred pounds. I was lucky
enough to be given a couple of metres as an 'offcut' by a gentleman
who worked in network support. You probably need something like that
if you're makng a 1m cable. But not for what the OP is trying to do. 
8:10 a.m.
On 6/28/23 09:40, Paul Koning via cctalk wrote:
> On Jun 28, 2023, at 9:48 AM, Tony Duell via cctalk <cctalk(a)classiccmp.org>
wrote:
>
> On Wed, Jun 28, 2023 at 6:00 AM Grant Taylor via cctalk
> <cctalk(a)classiccmp.org> wrote:
>> Tony's email makes me ask more questions than I have (smart alack)
>> answers to. Maybe ~> hopefully I can ~> will learn something.
> I was being a bit of a smart alec too. The point I was making is that
> a bit of normal IDC ribbon cable is not electrically the correct cable
> for an AUI interface but it won't matter over a few inches.
>
> The correct cable is 4 twisted pairs with a overall screen (shield).
> One pair is thicker wires than the other 3 and is used for the power.
> This cable was very hard to get by the metre when I needed some about
> 30 years ago, and a full reel was several hundred pounds. I was lucky
> enough to be given a couple of metres as an 'offcut' by a gentleman
> who worked in network support. You probably need something like that
> if you're makng a 1m cable. But not for what the OP is trying to do.
I did make up an AUI cable out of 4 separate shielded twisted-pair cables. Just
tie-wrapped them together.
Jon
6:44 a.m.
For a few inches, which would be enough here I think,
I've used an IDC
DA15 plug and socket crimped onto the normal ribbon cable. Technically
it's wrong but the reflections on that length of cable won't matter.
That's how Sun VME Ethernet boards are set up, the board itself is way back near the
VME connectors and small (or a Multibus in a converter, and small). Can't be too bad
if Sun did it on serious business workstations, right?!
Thanks,
Jonathan
6:53 a.m.
On Wed, Jun 28, 2023 at 2:44 PM Jonathan Chapman via cctalk
<cctalk(a)classiccmp.org> wrote:
As a PERQ-fanatic, I'd better not give my prejudiced views on Sun :-)
But seriously. Sun machines work on the ethernet just fine. So it
shows you can break the rules a bit...
-tony
For a few inches, which would be enough here I
think, I've used an IDC
DA15 plug and socket crimped onto the normal ribbon cable. Technically
it's wrong but the reflections on that length of cable won't matter.
That's how Sun VME Ethernet boards are set up, the board itself is way back near the
VME connectors and small (or a Multibus in a converter, and small). Can't be too bad
if Sun did it on serious business workstations, right?!
311
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311
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28 comments
12 participants
participants (12)
-
Bill Degnan -
Bill Gunshannon -
Cameron Kaiser -
Chris Zach -
Chris Zach -
Fred Cisin -
Grant Taylor -
Jon Elson -
Jonathan Chapman -
Martin Bishop -
Paul Koning -
Tony Duell