Another "how to connect my 2600?"-thread

[Kordanor]

Hey there! I got a Atari 2600 a while ago but don't have any means to display it at home (but I tested it before and know it works).

I haven't even owned a TV in my adult life, so I never had to fiddle around with an Antenna signal, which sounds quite confusing to me.

 

Ofc I already googled a bit, but didn't find much besides of several videos pointing towards buying a videorecorder to put in your RF Atari and convert it into something more useful. I also know of modding options, but I really don't want to solder anything. Quality of the picture in this instance isn't actually a primary concern (though you should be able to identify anything in the "snow"), so I would be cool with a somewhat noisy signal.

 

So a soldering mod is out of question. I am wondering if there is anything like a video recorder but which is more compact.

The signals I could use are HDMI, DVI, VGA and SVideo. I live in Germany in case this is of any relevance. I also looked into just capturing the signal on the PC via USB TV Tuners, but they come with descriptions such as "DVB-T2 HD, DVB-C HD, DVB-T", and after looking it up, seeing that it's digital and rather modern, I doubt this would actually work.

 

So does anyone know a cheap and not too cumbersome (get a video recorder / CRT TV) way to get the Atari RF signal to display on HDMI, DVI, VGA, SVideo or USB?

Edited December 15, 2022 by Kordanor
typo

[+x=usr(1536)]

54 minutes ago, Kordanor said:

So does anyone know a cheap and not too cumbersome (get a video recorder / CRT TV) way to get the Atari RF signal to display on HDMI, DVI, VGA, SVideo or USB?

One thing that's probably worth mentioning: whether you're using a CRT, video recorder, or other device, the first step in each case is going to be exactly the same - namely, connecting the 2600's RF output to that device's antenna input and tuning the device to UHF channel 36.  Using a CRT TV would be the simplest and most direct approach, but I don't know how realistic of an option that is for you.

 

To use a modern display input standard such as HDMI, DVI, etc. the first step will also be the same: convert the RF signal from the 2600 into composite (analogue), then convert that into your desired output type.  For this, you will want an RF demodulator daisy-chained to a composite-to-HDMI (etc.) converter; this can then be connected to your modern display of choice.

 

In all cases, the important thing to remember is that the console was originally designed to use the PAL TV system, so anything that you feed its signal to needs to be able to understand PAL.

 

One USB-based RF demodulator on eBay looks like it might be able to do what you need it to: https://www.ebay.com/itm/373708042347.  I have no experience with this particular unit, however, so can't comment on its effectiveness.

 

FWIW, many modern digital tuners do not have analogue tuners.  There is no good way of telling which do and don't without trying to connect to them unless they make a point of mentioning it on the box, etc.  Because of this many modern TVs won't be able to tune in the 2600's signal.

  

54 minutes ago, Kordanor said:

I haven't even owned a TV in my adult life, so I never had to fiddle around with an Antenna signal, which sounds quite confusing to me.

The 2600 has a tiny TV transmitter in it (the RF modulator), which broadcasts a signal on UHF channel 36.  By connecting it to the antenna input on a TV, video recorder, etc. and tuning to that channel, audio and video are shown on the TV.  It's really no different to tuning in a radio station, but with pictures added

[+-^CrossBow^-]

Que @BIGHMW now is your time to shine on this one as I believe you use something that might do exactly what the OP is wanting for the least amount of work/expense?

 

 

[Kordanor]

Thanks guys! I checked @BIGHMWs Posting history, and found his video. Checked some stuff (also found several bad reviews, including for the 2600), but as I didnt see anything better and the picture looks decent in the demo video I decided to try my luck. Also kinda funny that the store linked in the video sells it for $125.00, quite an increase. ^^
Amazon sells it for 30-50€ and I finally bought it directly at the source at aliexpress for 22€ + free shipping. Will let you know how it works out

[BIGHMW]

3 hours ago, Kordanor said:

Thanks guys! I checked @BIGHMWs Posting history, and found his video. Checked some stuff (also found several bad reviews, including for the 2600), but as I didnt see anything better and the picture looks decent in the demo video I decided to try my luck. Also kinda funny that the store linked in the video sells it for $125.00, quite an increase. ^^
Amazon sells it for 30-50€ and I finally bought it directly at the source at aliexpress for 22€ + free shipping. Will let you know how it works out

Cool! Thanks for the reference, I just hope that RF to HDMI converter works as well for you as it has for me, I've been using it for over 2 years and could never be more pleased with the results, it may not be perfect, but for Atari it certainly is the best bet if you don't want to modify your console.  Let me know how she works with your setup!!!

 

Ray Jackson 

[BIGHMW]

...and, for those who want to follow in @Kordanor's footsteps of for those who also want to know how to hook up YOUR 2600 or any other 70s/80s/90s console that runs on analog RF, here is my YouTube video on "that little rose gold-colored box" that is helping make retrogaming mainstream and putting Atari back on the map!!! ENJOY!!!

 

 

Edited December 16, 2022 by BIGHMW

[Kordanor]

The device arrived and I tested it in multiple ways. The results are...rather mixed. ^^

 

I connected the device to my HDMI screen, and I got a picture, but this picture was extremely snowy. Upon moving the cable it got better and worse and the cable has also seen better times. So I guess the snow in that case is down to the nature of RF and the quality of the cable. Probably no fault of the device.

 

However I tested a few other things:

1. I converted it to DVI-D. The monitor which also worked with HDMI did work as well. The other one did not get a signal.

2. I converted it to VGA. Monitor did not get a signal. The interesting part however is also that the audio could not be extracted.

 

3. I tried to capture the Signal via my Elgato HD60 S+, which did not work

4. I tried to just passthrough the Signal (hdmi in - hdmi out) in my Elgato HD60 S+ to the screen where HDMI did work. However this did not work.

5. I tried capturing the signal via DVI and my Datapath VisionRGB. That one did work. The result can be seen here (I just screencaptured the window, so you got a bit of border). This is how it also looks like on the screen.

 

So now I need to think about how to proceed. If I want to continue using RF I would probably need to buy a new RF cable....the snow is just so terrible that in a game like Asteroid you can't even see where you are shooting.

But I also intended to connect the device to a DVI-D or VGA Monitor. But that doesnt seem to be possible unfortunately.

Edited December 27, 2022 by Kordanor

[+-^CrossBow^-]

34 minutes ago, Kordanor said:

The device arrived and I tested it in multiple ways. The results are...rather mixed. ^^

 

I connected the device to my HDMI screen, and I got a picture, but this picture was extremely snowy. Upon moving the cable it got better and worse and the cable has also seen better times. So I guess the snow in that case is down to the nature of RF and the quality of the cable. Probably no fault of the device.

 

However I tested a few other things:

1. I converted it to DVI-D. The monitor which also worked with HDMI did work as well. The other one did not get a signal.

2. I converted it to VGA. Monitor did not get a signal. The interesting part however is also that the audio could not be extracted.

 

So now I need to think about how to proceed. If I want to continue using RF I would probably need to buy a new RF cable....the snow is just so terrible that in a game like Asteroid you can't even see where you are shooting.

But I also intended to connect the device to a DVI-D or VGA Monitor. But that doesnt seem to be possible unfortunately.

While I can't be sure on this as I don't own one of these devices. DVI and VGA do NOT have pins in their specs for carrying audio output while HDMI does. So that might explain why you weren't getting any audio using those formats. I know that I have to use an HDMI to DVI adapter in my work bench for testing RGB consoles, and I have to route the audio differently because the HDMI to DVI adapter does NOT pass through any audio.

 

 

[Kordanor]

Ah, yeah, I am aware of that. My HDMI to VGA Adapter does have HDMI IN, and VGA and Audio Out. But thats why it's strange. Even if VGA doesnt work, the Audio should work.

[+x=usr(1536)]

33 minutes ago, Kordanor said:

If I want to continue using RF I would probably need to buy a new RF cable

Make sure to get the shortest one that still lets you position the console where you want it - preferably as far away from the TV as possible.  If it has an RF choke on it, bonus.  Place the choke end at the console.

34 minutes ago, Kordanor said:

But I also intended to connect the device to a DVI-D or VGA Monitor. But that doesnt seem to be possible unfortunately.

There isn't really a good option for doing that on a 2600 without using an external converter of some sort.

 

I realise it's not your first choice, but feeding S-Video out from a UAV (along with audio, separately) to your capture device may be your best bet.  This can be done while keeping RF intact, and without drilling the case for RCA jacks, etc.

[+x=usr(1536)]

2 hours ago, Kordanor said:

I converted it to VGA. Monitor did not get a signal. The interesting part however is also that the audio could not be extracted.

I'm guessing that audio is being lost as part of the demodulation process for VGA, since that would likely be a three-step procedure: demodulate the RF into composite and audio, split composite into chroma and luma, and finally derive RGB from chroma and luma.  You'd think that demodulating the RF signal wouldn't result in dropping the audio, but anything is possible.

 

With the number of additional steps by which it's probably deriving RGB, there's plenty of opportunity for rejecting / mangling enough of each subsequent signal that what it ends up outputting may not be recognisable as SVGA to a number of devices.  IIRC, SVGA relies on sync-on-green in order to, uh, sync the picture   That RF demodulator may be completely stripping sync in one of the conversions steps, meaning that if it's not adding it back in the displays you have to hand don't see it as a valid SVGA signal because it isn't.

 

Take a look at the following blog entry:

 

 

That Sony demodulator may be a workable intermediate step for you in terms of ultimately getting DVI or HDMI to your display device without going the UAV route.  I'm not sure if that particular model support PAL signals or not, but there may be an equivalent model that does. @Nathan Strum: do you happen to know if yours is NTSC-only, or multi-standard?

[Kordanor]

3 hours ago, x=usr(1536) said:

I'm guessing that audio is being lost as part of the demodulation process for VGA, since that would likely be a three-step procedure: demodulate the RF into composite and audio, split composite into chroma and luma, and finally derive RGB from chroma and luma.  You'd think that demodulating the RF signal wouldn't result in dropping the audio, but anything is possible.

 

With the number of additional steps by which it's probably deriving RGB, there's plenty of opportunity for rejecting / mangling enough of each subsequent signal that what it ends up outputting may not be recognisable as SVGA to a number of devices.  IIRC, SVGA relies on sync-on-green in order to, uh, sync the picture   That RF demodulator may be completely stripping sync in one of the conversions steps, meaning that if it's not adding it back in the displays you have to hand don't see it as a valid SVGA signal because it isn't.

 

Take a look at the following blog entry:

 

 

That Sony demodulator may be a workable intermediate step for you in terms of ultimately getting DVI or HDMI to your display device without going the UAV route.  I'm not sure if that particular model support PAL signals or not, but there may be an equivalent model that does. @Nathan Strum: do you happen to know if yours is NTSC-only, or multi-standard?

Thanks. Checked the Blog Post (and the update here: https://forums.atariage.com/blogs/entry/17013-rf-addendum/ , but ofc thats also US based, not just with NTSC but also with the vendors. I checked to buy this mentioned  Belden 1505A, but Amazon doesnt offer it, and from other vendor I only found meterware where you also need to attach the endings). I mean if there was kind of a "cable assembly kit" I would be able to put it together I guess. But that way I fear that any single item is the source of buying something wrong. ^^

 

My plan would now be to use the RF->HDMI and then turn the HDMI into DVI and "record" that via my PC using VisionRGB. Meaning I got the screen on my PC and it should be possible to put that input on my 4/3 DVI screen (using HDMI->DVI). It's a bit overly complicated but should work and I got some more options for filtering and stuff (delay on VisionRGB is also super low). But ofc that original RF issue is still there (if the initial signal is crap, then you can only do so much).

Also I would need to find a way to extract the Audio from HDMI...as with HDMI->DVI that audio signal would get lost. So I need a way to split up the audio signal from hdmi I guess. But again, this is where it's weird, that the signal got lost not at HDMI but from HDMI -> VGA+Audio.

 

For those of you who have a better Idea of what fits to what:
If amazon doesn't have it, Conrad is also an electronics vendor which is videly availalable. So any recommendations there should likely be availably worldwide.

Edited December 27, 2022 by Kordanor

[BIGHMW]

Well @Kordanor, I'm glad you like the converter although you wish you had a better picture but you also gave me a damn good idea with regards to both of the RF cables I currently use with each my ColecoVision and my 5200.

 

Perhaps I should also take up the idea that @x=usr(1536) brought up and perhaps maybe order a few RG59 RF cables to hook them up with but also maybe put an RF choke on each one as well to quell down the RF interference even that much more, I just might do that.

Edited December 31, 2022 by BIGHMW

[BIGHMW]

On 12/27/2022 at 9:24 AM, Kordanor said:

The device arrived and I tested it in multiple ways. The results are...rather mixed. ^^

 

I connected the device to my HDMI screen, and I got a picture, but this picture was extremely snowy. Upon moving the cable it got better and worse and the cable has also seen better times. So I guess the snow in that case is down to the nature of RF and the quality of the cable. Probably no fault of the device.

 

However I tested a few other things:

1. I converted it to DVI-D. The monitor which also worked with HDMI did work as well. The other one did not get a signal.

2. I converted it to VGA. Monitor did not get a signal. The interesting part however is also that the audio could not be extracted.

 

3. I tried to capture the Signal via my Elgato HD60 S+, which did not work

4. I tried to just passthrough the Signal (hdmi in - hdmi out) in my Elgato HD60 S+ to the screen where HDMI did work. However this did not work.

5. I tried capturing the signal via DVI and my Datapath VisionRGB. That one did work. The result can be seen here (I just screencaptured the window, so you got a bit of border). This is how it also looks like on the screen.

 

So now I need to think about how to proceed. If I want to continue using RF I would probably need to buy a new RF cable....the snow is just so terrible that in a game like Asteroid you can't even see where you are shooting.

But I also intended to connect the device to a DVI-D or VGA Monitor. But that doesnt seem to be possible unfortunately.

Well from what I see in that clip you definitely are running it in the 4:3 mode as opposed to the 16:9 mode or "full" on the supplied remote as the "16:9" button does not have any function as I pointed out in my video, so I guess you like "old-skool"-style gaming and want to use the older-style display as opposed to having it (as one guy on my vid said) "stretched out", in other words using the full-screen/16:9 mode like I do.

[Kordanor]

12 hours ago, BIGHMW said:

Well from what I see in that clip you definitely are running it in the 4:3 mode as opposed to the 16:9 mode or "full" on the supplied remote as the "16:9" button does not have any function as I pointed out in my video, so I guess you like "old-skool"-style gaming and want to use the older-style display as opposed to having it (as one guy on my vid said) "stretched out", in other words using the full-screen/16:9 mode like I do.

Yeah, I switched it to 4:3 to get the right aspect ratio. But of course the signal will still be 1920x1080 (that's why it's captured as such). But that part is fine. I am surprised though, that my Screen with DVI-D and a resolution of 1600x1200 wasnt able to display it, even in 720p

Edited December 31, 2022 by Kordanor

[Kordanor]

Just a quick update:

Getting a RF cable replacement is much more of a pain in the ass than anticipated. I am starting to regret not going for the Composite replacement right away. ^^

Partly that is because of living in Europe. Let me explain:
-First thing you got to know is that EU has different RF connectors than US. And the fun thing is also that lots of stuff goes by different names. So just searching for it is a pain.

While US has Type F (screwed) Antenna connectors, Europe uses IEC connectors. Both are the standards, which also means that they are usually just called "Coax" (German: Koax) here. But searching for Coax obviously gets you nowhere as this is also just the cable type.

-To make it more interesting the European IEC in the US (or at least in that shop was was referred to) is just called PAL, adding one additional name to the list

-RF is also called HF in Germany, but that search term is useless anyways

-The connector on the Atari Board is Cinch, but Cinch is only colloquial, the real name is RCA. Ofc searching for either only gives you like half the possible results

-The Above mentioned gets worse if you combine RCA>IEC, Cinch->IEC, RCA->PAL...and so on

-The Atari cable RCA->IEC is rather special. Just the combination of RCA->IEC is a rarity, but also the RCA connection is not standard, as the pin is 9mm and usually the pin is 12+mm. Meaning that standard RCA Plugs dont work

-That means you need an adapter, but the space for an adapter is very small, so you need to get angles

-However these angles for these types are also not common

-The RCA Plug with the small Pin can only be found in US stores. I started to order there but then stopped, because in addition to the 10$ for the adapters (RCA->F Type, F Type->PAL) they wanted 50$ for shipping, and usually they will also ask for additional toll fees later on

-Alternatively you can saw down the plug. Not sure if that's any good, but thats likely what I need to do

 

In addition I also saw the hint that the RF Modulator Shield is garbage. That one needs to be connected to the RCA Ground as well. I tested that (just bridged it with a screwdriver) and the pic instantly got much better.

 

In any case, now I will try to get another angle and RCA/Cinch->IEC/Coax/PAL converter. As I killed the one I got (lets just say it wasnt very solid).

[+x=usr(1536)]

52 minutes ago, Kordanor said:

Just a quick update:

Getting a RF cable replacement is much more of a pain in the ass than anticipated. I am starting to regret not going for the Composite replacement right away. ^^

Partly that is because of living in Europe. Let me explain:
-First thing you got to know is that EU has different RF connectors than US. And the fun thing is also that lots of stuff goes by different names. So just searching for it is a pain.

What you may want to search for are DVB-T to F-Type antenna adapters.  I know that the nomenclature sounds weird, but they do come up searching that way.  FWIW, it will involve stacking an F-Type to RCA adapter on top of it, but it will get you where you want to be.

52 minutes ago, Kordanor said:

-To make it more interesting the European IEC in the US (or at least in that shop was was referred to) is just called PAL, adding one additional name to the list

DVB-T is also not very useful as a search term in the US due to North America using the ATSC TV standard.

52 minutes ago, Kordanor said:

-The connector on the Atari Board is Cinch, but Cinch is only colloquial, the real name is RCA. Ofc searching for either only gives you like half the possible results

-The Above mentioned gets worse if you combine RCA>IEC, Cinch->IEC, RCA->PAL...and so on

-The Atari cable RCA->IEC is rather special. Just the combination of RCA->IEC is a rarity, but also the RCA connection is not standard, as the pin is 9mm and usually the pin is 12+mm. Meaning that standard RCA Plugs dont work

-That means you need an adapter, but the space for an adapter is very small, so you need to get angles

-However these angles for these types are also not common

-The RCA Plug with the small Pin can only be found in US stores. I started to order there but then stopped, because in addition to the 10$ for the adapters (RCA->F Type, F Type->PAL) they wanted 50$ for shipping, and usually they will also ask for additional toll fees later on

-Alternatively you can saw down the plug. Not sure if that's any good, but thats likely what I need to do

My recommendation: build your own RCA-to-IEC cable.  Being completely honest, I couldn't find any good solutions that didn't involve stacking adapters, and, as you mention, space is tight so that likely wouldn't work.  Also, cutting down the centre pin on an RCA cable to fit the 2600's RF modulator is entirely possible; this was necessary in my 5200 to fit a right-angle adapter, and it works fine.

52 minutes ago, Kordanor said:

In addition I also saw the hint that the RF Modulator Shield is garbage. That one needs to be connected to the RCA Ground as well. I tested that (just bridged it with a screwdriver) and the pic instantly got much better.

Bear in mind that the 2600 was made in a time when things like WiFi, mobile phones, satellite TV, and so on either didn't exist or were very uncommon.  Only part of its function is to keep RF generated by the system in; its other one is to shield it from external RF sources.  It is strongly suggested that you repair the cause of the bad ground and rather than junking the shield.  You've already seen how it can (and does) affect the picture, so better to put it back the way it was intended to be.

[Kordanor]

6 hours ago, x=usr(1536) said:

What you may want to search for are DVB-T to F-Type antenna adapters.  I know that the nomenclature sounds weird, but they do come up searching that way. 

FWIW, it will involve stacking an F-Type to RCA adapter on top of it, but it will get you where you want to be.

DVB-T is also not very useful as a search term in the US due to North America using the ATSC TV standard.

Ah great, another search term to look for

In any case, if anyone had some luck finding something on ali-express, let me know. Thats probably the one retailer you can get stuff from for a decent price (shipping), no matter where you are. ^^

 

Quote

My recommendation: build your own RCA-to-IEC cable.  Being completely honest, I couldn't find any good solutions that didn't involve stacking adapters, and, as you mention, space is tight so that likely wouldn't work.  Also, cutting down the centre pin on an RCA cable to fit the 2600's RF modulator is entirely possible; this was necessary in my 5200 to fit a right-angle adapter, and it works fine.

Yeah, I think cutting it down seems the more solid solution than putting and soldering my own cable together.

 

Quote

It is strongly suggested that you repair the cause of the bad ground and rather than junking the shield.  You've already seen how it can (and does) affect the picture, so better to put it back the way it was intended to be.

I don't have any idea on how to identify that bad ground and what is considered "normal" there. Shouldnt the antenna ground be as good as any other ground connection?

[+x=usr(1536)]

4 hours ago, Kordanor said:

I don't have any idea on how to identify that bad ground and what is considered "normal" there.

It will take some trial and error.  Since you mentioned bridging the RF modulator shield to the RCA ground and getting a better picture, those two would probably be your best starting points.

 

FWIW, the modulator grounds directly to the PCB.  On the underside of the PCB, directly beneath the modulator, you should see four tabs.  They'll have very heavy solder joints, and will be laid out in a rectangular pattern; those are the modulator grounds.  Reflowing the solder on those tabs may not be a bad starting point.  Also checking the RCA connector would be a good idea - they can become loose or detached from the modulator over time.

 

Out of curiosity, as I don't recall seeing it mentioned before, which model of 2600 is this - a Woody, Vader, or Junior?

4 hours ago, Kordanor said:

Shouldnt the antenna ground be as good as any other ground connection?

Absolutely.  If it isn't, something's not right.

[Kordanor]

I will go for the route with sawing down the Pin. Checked back with an electronics store in Karlsruhe, and he was saying that the length of the pin is a norm, and the Atari doesnt match it. Cool dude though, recommend the shop (muekra) in any case anyone lives there ^^

 

Regarding the ground, I will look further into it, once the RF cable is "fixed" to get a more stable baseline.

 

It's the ancient model, the Woody.

[BIGHMW]

Well taking a cue from @Kordanor, I believe that Best Electronics just might still have some OEM RCA/IEC RF cords for the European market available and maybe I should look into getting some (well may the maximum order of 3 for Best's ordering rules) and maybe swap the 5200 cord with it and also use the other one with my ColecoVision and have a spare one as well just in case. Then maybe I can look into an IEC 2 way splitter or switcher so I can have both consoles ready and have a short IEC cord hooked up to the converter, no more adapters to get in the way and degrade the signal!!!

[Kordanor]

Do you have an URL for that store? I checked, and found a store in Germany and in Portugal with that name and 2 in the US, but none had parts like this. ^^

[+x=usr(1536)]

41 minutes ago, Kordanor said:

Do you have an URL for that store? I checked, and found a store in Germany and in Portugal with that name and 2 in the US, but none had parts like this. ^^

I will warn you in advance: this is not e-commerce like you're used to it.  Think of it as ordering parts for your 1980s video game console the way that they would have been ordered in the 1980s.

 

https://www.best-electronics-ca.com/

 

The owner (Brad) is perfectly fine to order from, but you will almost certainly need to do it by phone.  I would suggest dropping him an email message detailing what you need and that you are in Germany.  It might not hurt to throw some more items into the pile since he typically does better with orders in the $50-and-up range.

 

Failing that, if he has them, one of us could add it to an order and forward it on to you.  Honestly, that would probably be the best approach.

[Kordanor]

Well, I do have something coming now although the pin is the wrong size. I will saw it dawn and check if that works sufficiently.

But even if shipping will not be 50$, it will probably be expensive from the US.

 

And holy cow...what a homepage...

[BIGHMW]

2 hours ago, Kordanor said:

And holy cow...what a homepage...

.... it's a mess isn't it? But, please do make sure that when you do place your order that you have the correct part number and for that you'll need to be both logged onto that site at the specific part of it where those cords are located at and be on the phone at the same time so you have the proper exact info on those cords. I myself plan on also ordering them for my 2 consoles (3 cords total as mentioned in my previous post) but will wait for you to place your order first so you can get yours and then I'll place mine. Brad does thing a little different, in fact, he does them, well, as we Americans would say, kind of "old school", via phone with the website being merely a source of the exact info you'll need, and, another thing, make sure you be a little easy on him, speak slowly, after all, he has to write everything down while taking your order, and, oh yes, one more thing, he only takes cards (VISA or Mastercard or European equivalent, I'm sure they can do the exchange rate from Euros to US dollars and vice-versa, consult your card company or bank before doing so), he stopped taking PayPal years ago, hopefully he'll get into the 2020s soon, but mostly its like ordering in the late 80's-early 90's, like from a catalog store or off of one of those TV offers used to be like, over the phone with the website in this case acting merely as an online catalog.

Edited January 11, 2023 by BIGHMW