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Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA)

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  Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA) Rh Kramer <rhkramer.s31@gmail.com> - 2020-11-28 15:10 +0100
    Re: Advice on laptop with USB-C port and USB-Type C Multipoint  Adapter (and VGA) Dan Ritter <dsr@randomstring.org> - 2020-11-28 18:00 +0100
    Re: Advice on laptop with USB-C port and USB-Type C Multipoint  Adapter (and VGA) Andrei POPESCU <andreimpopescu@gmail.com> - 2020-11-29 07:30 +0100
      Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA) Stefan Monnier <monnier@iro.umontreal.ca> - 2020-11-29 18:30 +0100
      Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA) rhkramer@gmail.com - 2020-12-02 16:30 +0100
        Re: Advice on laptop with USB-C port and USB-Type C Multipoint  Adapter (and VGA) Andrei POPESCU <andreimpopescu@gmail.com> - 2020-12-02 17:00 +0100
          Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA) rhkramer@gmail.com - 2020-12-02 17:50 +0100
        Re: Advice on laptop with USB-C port and USB-Type C Multipoint  Adapter (and VGA) David <bouncingcats@gmail.com> - 2020-12-03 10:40 +0100
          Re: Advice on laptop with USB-C port and USB-Type C Multipoint  Adapter (and VGA) <tomas@tuxteam.de> - 2020-12-03 11:20 +0100
            Re: Advice on laptop with USB-C port and USB-Type C Multipoint  Adapter (and VGA) David <bouncingcats@gmail.com> - 2020-12-03 11:40 +0100
              Re: Advice on laptop with USB-C port and USB-Type C Multipoint  Adapter (and VGA) <tomas@tuxteam.de> - 2020-12-03 11:50 +0100
                Re: Advice on laptop with USB-C port and USB-Type C Multipoint  Adapter (and VGA) David <bouncingcats@gmail.com> - 2020-12-03 22:10 +0100
              Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA) rhkramer@gmail.com - 2020-12-03 15:00 +0100
                Re: Advice on laptop with USB-C port and USB-Type C Multipoint  Adapter (and VGA) David <bouncingcats@gmail.com> - 2020-12-03 22:10 +0100
            Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA) rhkramer@gmail.com - 2020-12-03 15:00 +0100
          Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA) rhkramer@gmail.com - 2020-12-03 15:00 +0100
            Re: Advice on laptop with USB-C port and USB-Type C Multipoint  Adapter (and VGA) Andrei POPESCU <andreimpopescu@gmail.com> - 2020-12-04 11:10 +0100

#229152 — Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA)

Advice on laptop with USB-C port and USB-Type C Multipoint Adapter

Background: a few months ago, I bought a generic / inexpensive USB-Type C 
Multipoint Adapter (with VGA output) and around the same time ordered a laptop 
that advertised a USB-C port.  When I received the laptop, I saw that it did 
not have the USB-C port, so I returned it.  I kept the USB-Type C Multipoint 
Adapter.  I also started digging into the USB-Type C port and learned that 
there are several variations -- some that support video and some that do not.

(I guess a key thing is USB-C "alternate mode" which, iiuc, under some 
variations, can support video -- I strongly suspect that not all 
implementations of alternate-mode support video, and even less so, all 
variations of video.)

Yesterday, I almost bought a HP Pavilion Laptop model 15z-eh000, but was 
uncertain it would work the way I wanted, and today the price has gone back up 
by $120, so I'm not anxious to buy it atm.  But, I want to understand more  so 
that when I find a laptop that I want to buy I can confirm that it meets my 
needs.

My needs:

   * first, I want to hook it up to my KVM switch (with two other computers), 
install Buster on it (and C++ version 20 (or whatever they call it)) and use 
it for development of a lexer for Scintilla.  

   * second, as a  laptop, I expect on rare occasions to disconnect it from my 
KVM switch to use it portably
   
Other information:

The KVM switch has VGA input and output, and the Multipoint adapter has USB-C 
input and, among other things, a VGA output (and RJ-45  for Ethernet, bbut no 
HDMI, which would be irrelevant anyway in view of the KVM switch and my VGA 
monitor).

Below I quote some information from various web pages I looked at with respect 
to the HP 15z-eh000, and here is the "specification" for the (2) USB-C ports:

"1 SuperSpeed USB Type-C® 10Gbps signaling rate (USB Power Delivery, 
DisplayPort™ 1.4, HDMI 1.4, HP Sleep and Charge)(with AMD Athlon™ Gold 
processor);" 

So, (some of) my questions:

Would that laptop work with Buster and my Multiport adapter with VGA adapter?

Does Buster support DisplayPort?  (Do I need to have DisplayPort supported?)

If I had a multiport adapter with HDMI output would it work with that laptop?  
(Not that that would work with my KVM switch, but it provides a little extra 
information to me, and I could consider an HDMI to VGA adapter in the 
"chain".)

Thanks for any input!  Extra credit if you can claim experience with actual 
devices ;-)

Some web page resources:

https://laptoping.com/specs/product/hp-15z-eh000/
`
Video ports 	Video out via USB-C
'

https://store.hp.com/us/en/slp/black-friday-sale?source=aw&subacctid=166580&subacctname=Slickdeals&adcampaigngroup=111627&awc=7168_1606504159_c1fb74e828bbeb9317783c20cd6c719b&jumpid=af_gen_nc_ns&utm_medium=af&utm_source=aw&utm_campaign=Slickdeals

HP Pavilion Laptop - 15z-eh000 touch optional
`
External I/O Ports
1 SuperSpeed USB Type-C® 10Gbps signaling rate (USB Power Delivery, 
DisplayPort™ 1.4, HDMI 1.4, HP Sleep and Charge)(with AMD Athlon™ Gold 
processor); 1 SuperSpeed USB Type-C® 10Gbps signaling rate (USB Power 
Delivery, DisplayPort™ 1.2, HDMI 2.0, HP Sleep and Charge)(with AMD Ryzen™ 
3/5/7 processor); 1 headphone/microphone combo
[19]

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#229153 — Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA)

Rh Kramer wrote: 
> The KVM switch has VGA input and output, and the Multipoint adapter has USB-C 
> input and, among other things, a VGA output (and RJ-45  for Ethernet, bbut no 
> HDMI, which would be irrelevant anyway in view of the KVM switch and my VGA 
> monitor).
> 
> Below I quote some information from various web pages I looked at with respect 
> to the HP 15z-eh000, and here is the "specification" for the (2) USB-C ports:
> 
> "1 SuperSpeed USB Type-C?? 10Gbps signaling rate (USB Power Delivery, 
> DisplayPort??? 1.4, HDMI 1.4, HP Sleep and Charge)(with AMD Athlon??? Gold 
> processor);" 
> 
> So, (some of) my questions:
> 
> Would that laptop work with Buster and my Multiport adapter with VGA adapter?

ALmost certainly.

> Does Buster support DisplayPort?  (Do I need to have DisplayPort supported?)

Yes, and not especially.

> If I had a multiport adapter with HDMI output would it work with that laptop?  

Almost certainly.

In particular: the Ryzen APUs have a Radeon GPU that is
well-supported by Debian. You will want to add the amd non-free
firmware, but unless you have really high-performance graphics
needs, you won't need anything not shipped by Debian in Buster.


-dsr-

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#229162 — Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA)

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On Sb, 28 nov 20, 09:07:14, Rh Kramer wrote:
> Advice on laptop with USB-C port and USB-Type C Multipoint Adapter
> 
> Background: a few months ago, I bought a generic / inexpensive USB-Type C 
> Multipoint Adapter (with VGA output) and around the same time ordered a laptop 
> that advertised a USB-C port.  When I received the laptop, I saw that it did 
> not have the USB-C port, so I returned it.  I kept the USB-Type C Multipoint 
> Adapter.  I also started digging into the USB-Type C port and learned that 
> there are several variations -- some that support video and some that do not.

It's useful to remember that Type C refers only to the shape of a 
connector, whereas USB (in it's various versions) refers to a bus that 
can be used to connect various external devices to a computer.

The Type C connector may or may not be used for (a combination of) USB
(usually 3.0 or higher) _and/or_ power delivery _and/or_ *digital* 
display output (and possibly more I don't know about).

> (I guess a key thing is USB-C "alternate mode" which, iiuc, under some 
> variations, can support video -- I strongly suspect that not all 
> implementations of alternate-mode support video, and even less so, all 
> variations of video.)

Regarding video output you have to consider that VGA is analog whereas 
DisplayPort and HDMI are digital.

As far as I understand, a USB to VGA adapter is basically just a video 
card that just happens to connect via USB (instead of PCI-E or so), 
while USB to HDMI (or DisplayPort) adapters could be either an external 
video adaptor connected via USB or using "alternate mode" to route the 
digital video signal directly from the internal video adapter to the 
display (only possible with a Type C connector).

Hope this helps,
Andrei
-- 
http://wiki.debian.org/FAQsFromDebianUser

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#229166

> As far as I understand, a USB to VGA adapter is basically just a video 
> card that just happens to connect via USB (instead of PCI-E or so),

It could also be that its "USB-C to VGA" converts the displayport signal
to VGA (in which case it will only work with those type C connectors
which provide a displayport signal).


        Stefan

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#229219

Thanks to all who replied -- I have some notes at the bottom of this email.

On Sunday, November 29, 2020 01:27:12 AM Andrei POPESCU wrote:
> On Sb, 28 nov 20, 09:07:14, Rh Kramer wrote:
> > Advice on laptop with USB-C port and USB-Type C Multipoint Adapter

> > (I guess a key thing is USB-C "alternate mode" which, iiuc, under some
> > variations, can support video -- I strongly suspect that not all
> > implementations of alternate-mode support video, and even less so, all
> > variations of video.)
> 
> Regarding video output you have to consider that VGA is analog whereas
> DisplayPort and HDMI are digital.
> 
> As far as I understand, a USB to VGA adapter is basically just a video
> card that just happens to connect via USB (instead of PCI-E or so),
> while USB to HDMI (or DisplayPort) adapters could be either an external
> video adaptor connected via USB or using "alternate mode" to route the
> digital video signal directly from the internal video adapter to the
> display (only possible with a Type C connector).
> 
> Hope this helps,

Yes, thanks, it is certainly a good start.

My current take on the subject is this:

   * I don't have enough knowledge (yet) to confidently pick a laptop that will 
work with the multiport adapter I bought with VGA output

   * I have some amount of faith that this particular laptop would work 
because one of the accessories available for it is a USB-C to VGA adapter

   * I am skeptical that I could get a reliable answer on the subject from HP 
(or any other laptop manufacturer) -- one of my indicators might be to see if 
the manufacturer has a USB-C to VGA adapter for that laptop, but, still it 
might not work with the multiport adapter

Aside: I had called it a multipoint adapter, it is a multiport adapter.

I have started reading (and will continue, probably slowly) to dig into 
DisplayPort and DisplayLink and related stuff

I did find out that a USB-C cable / connector has 24 conductors -- so it is 
conceivable (with my lack of knowledge) that some laptop manufacturers 
actually put out an (analog) VGA signal on the USB-C cable.

Conclusion: for now, I'm not going to rush to buy a laptop.  I may look for a 
mini-PC (something close to the size of a laptop) with VGA output (and things 
like an AMD processor, memory expandable to 16 GB, ...) for my development 
efforts in Buster (or maybe wipe out the Jessie installation (or make it a dual 
boot) with Buster -- I can't give up Wheezy at this point, and I really don't 
have too much "invested" in Jessie at this point.

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#229220 — Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA)

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On Mi, 02 dec 20, 10:26:43, rhkramer@gmail.com wrote:
> 
>    * I don't have enough knowledge (yet) to confidently pick a laptop that will 
> work with the multiport adapter I bought with VGA output

It would probably help to determine whether the multiport adapter 
contains a VGA video chip connected via USB or just a DAC for 
DisplayPort the signal that may or may not be present, depending on the 
laptop (see also Stefan's reply).

Kind regards,
Andrei
-- 
http://wiki.debian.org/FAQsFromDebianUser

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#229223

On Wednesday, December 02, 2020 10:56:24 AM Andrei POPESCU wrote:
> On Mi, 02 dec 20, 10:26:43, rhkramer@gmail.com wrote:
> >    * I don't have enough knowledge (yet) to confidently pick a laptop
> >    that will
> > 
> > work with the multiport adapter I bought with VGA output
> 
> It would probably help to determine whether the multiport adapter
> contains a VGA video chip connected via USB or just a DAC for
> DisplayPort the signal that may or may not be present, depending on the
> laptop (see also Stefan's reply).

Yeah -- I haven't found anything in the "instruction sheet" that came with it, 
near as I can tell it is a generic (i.e., far east / china thing) with 
(model?) number ULS-CP1V1L2A.

Google didn't give me anything helpful.

I can think about taking it apart, but there are no obvious clues (screws) as 
to how -- maybe it is snapped together (or glued).

Anyway, it wasn't that expensive, so if I end up not using it, it is not a big 
loss.  (But I do need VGA output from the laptop somehow (to connect to my KVM 
switch) and would like to have some kind of docking device that requires only 
one cable to connect or disconnect the laptop (in addition to a power supply 
(or not, if it can be powered through the USB-C connector)).)

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#229238 — Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA)

On Thu, 3 Dec 2020 at 02:27, <rhkramer@gmail.com> wrote:

> I did find out that a USB-C cable / connector has 24 conductors -- so it is
> conceivable (with my lack of knowledge) that some laptop manufacturers
> actually put out an (analog) VGA signal on the USB-C cable.

Is this just wishful thinking or do you have evidence?

Because it's inconceivable, as far as I'm aware. Everything I have read
about USB-C indicates that it is purely digital. Even though it seems
to be the USB way to have countless variations of every physical and
electrical specification, VGA is a standard from 1987, forget finding
it on any USB-C connector. Those pins are all used for other things.

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#229239 — Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA)

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On Thu, Dec 03, 2020 at 08:35:37PM +1100, David wrote:
> On Thu, 3 Dec 2020 at 02:27, <rhkramer@gmail.com> wrote:
> 
> > I did find out that a USB-C cable / connector has 24 conductors -- so it is
> > conceivable (with my lack of knowledge) that some laptop manufacturers
> > actually put out an (analog) VGA signal on the USB-C cable.
> 
> Is this just wishful thinking or do you have evidence?
> 
> Because it's inconceivable, as far as I'm aware. Everything I have read
> about USB-C indicates that it is purely digital. Even though it seems
> to be the USB way to have countless variations of every physical and
> electrical specification, VGA is a standard from 1987, forget finding
> it on any USB-C connector. Those pins are all used for other things.

USB-C is a mess. Quoth [1]:

   "A device with a Type-C connector does not necessarily
   implement USB, USB Power Delivery, or any Alternate Mode:
   the Type-C connector is common to several technologies while
   mandating only a few of them"

That said, Display Port, Thunderbolt, MHL and HDMI alternate modes seem
to implement VGA output with an "active" cable, which is an euphemism
for "there's some chips in there".

So your computer's USB-C socket must fit, your dongle, aka "active
cable" must fit, and they have to be capable to talk to each other.

Cheers
 - t

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#229240 — Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA)

On Thu, 3 Dec 2020 at 21:15, <tomas@tuxteam.de> wrote:
> On Thu, Dec 03, 2020 at 08:35:37PM +1100, David wrote:
> > On Thu, 3 Dec 2020 at 02:27, <rhkramer@gmail.com> wrote:

> > > I did find out that a USB-C cable / connector has 24 conductors -- so it is
> > > conceivable (with my lack of knowledge) that some laptop manufacturers
> > > actually put out an (analog) VGA signal on the USB-C cable.

> > Is this just wishful thinking or do you have evidence?

> > Because it's inconceivable, as far as I'm aware. Everything I have read
> > about USB-C indicates that it is purely digital. Even though it seems
> > to be the USB way to have countless variations of every physical and
> > electrical specification, VGA is a standard from 1987, forget finding
> > it on any USB-C connector. Those pins are all used for other things.

> USB-C is a mess. Quoth [1]:
>
>    "A device with a Type-C connector does not necessarily
>    implement USB, USB Power Delivery, or any Alternate Mode:
>    the Type-C connector is common to several technologies while
>    mandating only a few of them"
>
> That said, Display Port, Thunderbolt, MHL and HDMI alternate modes seem
> to implement VGA output with an "active" cable, which is an euphemism
> for "there's some chips in there".
>
> So your computer's USB-C socket must fit, your dongle, aka "active
> cable" must fit, and they have to be capable to talk to each other.

Does the active cable have a USB-C connector on the VGA end?
The comment I responded to speaks of analog VGA signals
on a USB-C connector.

I thought "that's weird" so before I wrote I had a quick read of all the main
links under the heading
  https://en.wikipedia.org/wiki/USB-C#Alternate_Mode_partner_specifications
and I saw no trace of any such thing.

As always, I'm happy to be corrected if wrong. I take no interest in
"active cables" myself, modern passive cables are unreliable enough,
but if someone wants to provide a link then I will enjoy a chuckle that
someone somewhere thinks this is good engineering.

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#229241 — Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA)

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On Thu, Dec 03, 2020 at 09:35:38PM +1100, David wrote:
> On Thu, 3 Dec 2020 at 21:15, <tomas@tuxteam.de> wrote:

[...]

> > USB-C is a mess. Quoth [1]:

[...]

> Does the active cable have a USB-C connector on the VGA end?

Yes, it should.

> The comment I responded to speaks of analog VGA signals
> on a USB-C connector.

Going by the Wikipedia reference, no. Unless/until there's an Alternate
Mode defining that; I can't imagine this is going to happen.

> I thought "that's weird" so before I wrote I had a quick read of all the main
> links under the heading
>   https://en.wikipedia.org/wiki/USB-C#Alternate_Mode_partner_specifications
> and I saw no trace of any such thing.

For that to happen, there must be some entity with enough stamina and
financial power to back a hypothetical VGA Alternate Mode. Who would
have interest in that?

> As always, I'm happy to be corrected if wrong. I take no interest in
> "active cables" myself, modern passive cables are unreliable enough,
> but if someone wants to provide a link then I will enjoy a chuckle that
> someone somewhere thinks this is good engineering.

Tickling your favourite search engine (let's hope it ain't Google ;-)
yields tons of "USB-C to VGA" adapters. For all we know, they should
be "active".

Those things aren't driven by engineering. They are driven by marketing.

Cheers
 - t

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#229261 — Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA)

On Thu, 3 Dec 2020 at 21:49, <tomas@tuxteam.de> wrote:
> On Thu, Dec 03, 2020 at 09:35:38PM +1100, David wrote:
> > On Thu, 3 Dec 2020 at 21:15, <tomas@tuxteam.de> wrote:

> > Does the active cable have a USB-C connector on the VGA end?
>
> Yes, it should.

> Tickling your favourite search engine (let's hope it ain't Google ;-)
> yields tons of "USB-C to VGA" adapters. For all we know, they should
> be "active".

I searched as you suggest, everything that I can find appears to
put the VGA signals on a DB15 connector, not a USB-C connector.

What I am seeking evidence for (just out of simple WTF curiosity :)
is that somewhere in the world there exists a USB-C connector
that carries VGA analog signals.

Not an adapter, a connector.

I don't want one, I don't need one, and I don't even care except for
entertainment, I just struggle to believe that such a thing exists until
I see a picture or a document :)

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#229247

On Thursday, December 03, 2020 05:35:38 AM David wrote:
> Does the active cable have a USB-C connector on the VGA end?
> The comment I responded to speaks of analog VGA signals
> on a USB-C connector.

If you are asking about the multiport adapter that I have, there is a small 
enclosed module (of some sort) in a small, not easily / obviously openable, 
enclosure, with "sockets" for VGA, (2x) USB (the old style large connector), 
RJ-45, USB-C.  There is an attached short cable with a USB-C plug on the end 
to connect to a laptop.


> I thought "that's weird" so before I wrote I had a quick read of all the
> main links under the heading
>   https://en.wikipedia.org/wiki/USB-C#Alternate_Mode_partner_specifications
> and I saw no trace of any such thing.
> 
> As always, I'm happy to be corrected if wrong. I take no interest in
> "active cables" myself, modern passive cables are unreliable enough,
> but if someone wants to provide a link then I will enjoy a chuckle that
> someone somewhere thinks this is good engineering.

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#229262 — Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA)

On Fri, 4 Dec 2020 at 00:58, <rhkramer@gmail.com> wrote:

> If you are asking about the multiport adapter that I have, there is a small
> enclosed module (of some sort) in a small, not easily / obviously openable,
> enclosure, with "sockets" for VGA, (2x) USB (the old style large connector),
> RJ-45, USB-C.  There is an attached short cable with a USB-C plug on the end
> to connect to a laptop.

Hi Randy,

Thanks for clarifying :)

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#229249

Thanks!

On Thursday, December 03, 2020 05:15:12 AM tomas@tuxteam.de wrote:
> USB-C is a mess. Quoth [1]:
> 
>    "A device with a Type-C connector does not necessarily
>    implement USB, USB Power Delivery, or any Alternate Mode:
>    the Type-C connector is common to several technologies while
>    mandating only a few of them"
> 
> That said, Display Port, Thunderbolt, MHL and HDMI alternate modes seem
> to implement VGA output with an "active" cable, which is an euphemism
> for "there's some chips in there".
> 
> So your computer's USB-C socket must fit, your dongle, aka "active
> cable" must fit, and they have to be capable to talk to each other.

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#229248

On Thursday, December 03, 2020 04:35:37 AM David wrote:
> On Thu, 3 Dec 2020 at 02:27, <rhkramer@gmail.com> wrote:
> > I did find out that a USB-C cable / connector has 24 conductors -- so it
> > is conceivable (with my lack of knowledge) that some laptop
> > manufacturers actually put out an (analog) VGA signal on the USB-C
> > cable.
> 
> Is this just wishful thinking or do you have evidence?

Well, I guess it could be called wishful thinking, but I tried to be pretty 
clear where I was coming from: "it is conceivable (with my lack of knowledge) 
that some laptop manufacturers actually put out an (analog) VGA signal on the 
USB-C cable.

But I don't know what those 24 conductors are for, and I thought it was 
possible some were reserved for future use (or with the alternate modes) -- I 
guess your answer clarifies that there aren't any such "spare" conductors.

Thanks for your reply!

> 
> Because it's inconceivable, as far as I'm aware. Everything I have read
> about USB-C indicates that it is purely digital. Even though it seems
> to be the USB way to have countless variations of every physical and
> electrical specification, VGA is a standard from 1987, forget finding
> it on any USB-C connector. Those pins are all used for other things.

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#229288 — Re: Advice on laptop with USB-C port and USB-Type C Multipoint Adapter (and VGA)

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On Jo, 03 dec 20, 08:49:58, rhkramer@gmail.com wrote:
> On Thursday, December 03, 2020 04:35:37 AM David wrote:
> > On Thu, 3 Dec 2020 at 02:27, <rhkramer@gmail.com> wrote:
> > > I did find out that a USB-C cable / connector has 24 conductors -- so it
> > > is conceivable (with my lack of knowledge) that some laptop
> > > manufacturers actually put out an (analog) VGA signal on the USB-C
> > > cable.
> > 
> > Is this just wishful thinking or do you have evidence?
> 
> Well, I guess it could be called wishful thinking, but I tried to be pretty 
> clear where I was coming from: "it is conceivable (with my lack of knowledge) 
> that some laptop manufacturers actually put out an (analog) VGA signal on the 
> USB-C cable.
> 
> But I don't know what those 24 conductors are for, and I thought it was 
> possible some were reserved for future use (or with the alternate modes) -- I 
> guess your answer clarifies that there aren't any such "spare" conductors.
 
I know from experience what a difference it makes to use a better 
(typically thicker) VGA cable, especially over longer distances.

Even the high quality USB-C cables with support for power delivery are 
thinner than a VGA cable. There's no "room" for analog signals there.  
Similar for the connector.
 
> > Because it's inconceivable, as far as I'm aware. Everything I have read
> > about USB-C indicates that it is purely digital. Even though it seems
> > to be the USB way to have countless variations of every physical and
> > electrical specification, VGA is a standard from 1987, forget finding
> > it on any USB-C connector. Those pins are all used for other things.

Display devices manufactured in the last (10? 20?) years are using 
digital technology (LCD, OLED, etc.) and have a digital input port (DVI, 
HDMI or DisplayPort[1]).

Conversion to (video card to VGA output) and from analog (VGA input to 
digital display) is wasting money for the DAC/ADC and signal quality[2].

It wouldn't make sense to "hold back" a new connector like Type C with 
support for analog signals (besides the size requirements). These USB to 
VGA adapters are meant for older devices without a digital input that 
are still worth keeping around (e.g. projectors).

[1] DVI, HDMI and DisplayPort are signal compatible, conversion is done 
with passive adaptors or cables.
[2] do yourself a favour and use a digital connection between computer 
and display device whenever possible.

Kind regards,
Andrei
-- 
http://wiki.debian.org/FAQsFromDebianUser

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