Slashdot Mirror

← Back to Stories (view on slashdot.org)

Using Old Laptops as Pass-Thru Displays?

Posted by Cliff on from the laptop-displays-are-better-than-crappy-monitors! dept.

Wirenut asks: "After another WinDOZE based round of laptop upgrades, I've got a pile of Toshiba (among other) laptops with beautiful displays and crappy processors. Anybody know a techie-way of making these work as flat-panels for regular PC's? I could save a lot of room om my tech bench. PS> I'm pretty handy with a soldering iron, so let me have it. " Interesting thought. Could something like this really work?

33 comments

  1. RE: Crappy Laptop Processors... by Cheerio+Boy · · Score: 1

    I suppose you could get the techincal specs from Toshiba or whoever made the laptops. (I know IBM keeps its specs on-line.)

    However you may have another option if the notebooks are 486. There's a company that's an offshoot of Evergreen called Maximum Upgrades Inc. They uprade 486 notebooks to AMD 5x86 chips at anywhere from 100mhz to 133mhz depending on the notebook. One of the best options because at that point these will be decent Linux notebooks or even portable small servers. :-)

    --

    "Bah!" - Dogbert
  2. Serial consoles by platinum · · Score: 1

    I'm sure the laptops have at least one serial port. *BSD, Solaris, Linux >= 2.1.x, and most other Unices have serial console support in some respect. Why waste $$$ on new monitors and keyboards for those servers... Install Linux or *BSD on the laptop, install minicom, and away you go :)

  3. One obvious solution... by Phil-14 · · Score: 1

    One obvious solution would be to put ethernet on these laptops, and use them as X terminals. It should take a lot less processor power than using them as a whole machine.


    --
    (currently testing something about signatures here)
    1. Re:One obvious solution... by dattaway · · Score: 2

      Using old 486 laptops as xterms works *very* well with an ethernet card. Just export the displays you wish and your main box will appear to have many heads. Just ifconfig the ip, export the display, and set xhosts on the remote to allow the access. It takes a few minutes and the results are low powered heads displaying lots of additional screen realestate.

  4. Lets do it...Old pc's make GREAT linux terminals by Anonymous Coward · · Score: 0

    I am using old pc's as terminals on our linux boxen, even 4.77 8088's. They have better keyboards :-) I use XFS (Simtel mirror) which seems to have disappeared :-( and mount a linux path as a local drive letter. It works GREAT :-) I can also mount Linux printers, no sweat. The only problem is that it doesn't currently work with freeDOS. However, we all really need a piece of software which would: 1. run x windows on the server to a dummy screen, memory image, on the server. 2. A simple mirror program so that, that screen would be sent to and displayed on on the given pc. This could be a simple freeDOS based program. 3. Also, the I/O ports (serial, parallel, etc.) of that PC could be mapped as devices on the Linux serverso that simple shell/perl scripts on the 'server' could control the peripheral processor. One old PC could be an easily rebootable modem pool, another a Hercules based B+W X windows terminal. All out of currently unused 'junk'. (I still preferr B+W Herc.) I wish I were smart enough to make the necessary RPM's and freeDOS software. But, alas I am not. I need HELP. Happy Linuxing to all. emanon

  5. Re: Crappy Laptop Processors... by tallpaul · · Score: 1

    Hey, just go for it. If you're that handy with a soldering iron, try replacing the clock crystal and see if you can overclock those suckers.

    Think about it -- the worst you can do is nuke one of them. I think if you are careful about how you dismember it, and take good notes, you could even hook the dismembered one back up well enough to function.

    I usually end up with junk for my hardware hacking troubles, but I always have fun.

  6. Re:Lets do it...Old pc's make GREAT linux terminal by snookums · · Score: 1

    Indeed old boxen == good xterminals.
    The "dummy server" you talk about exists in the form of VNC. However, the client requires MS-Windows or another X server (perhaps Xappeal??)

    --
    Be careful. People in masks cannot be trusted.
  7. Similar question... by snookums · · Score: 1

    I have some nice old 19" B&W screens off some NCD xterms that bit the dust. I'd like to hook them up to the VGA cards of linux x-boxen. Is this possible?
    The pinout for the connector is available from the NCD website, but I don't know what to connect together. Do I just plug the sync lines in, then hook the signal up to the green or what?
    Any hints would be appreciated - my eyes are going nuts coding on my blury 5yo 15"

    --
    Be careful. People in masks cannot be trusted.
    1. Re:Similar question... by dfung · · Score: 1

      This is definitely one of those "yeah, but..." answers.

      There's no doubt that most cards will be able to support your displays. The hardware part will probably be fairly simple. The problem will be that you will likely require some Software(tm). And we all know what that means...

      From a hardware standpoint, you need to examine the sync requirement of the display. They come three ways - separate Horizontal (H) and Vertical (V) syncs on two lines, composite sync where both H and V are on the same line, and sync-on-green where the H and V signals are combined with the green video signal. I'll be pretty obvious when you see the pinout.

      For the hobbyist, you can easily cheat. If you have sync-on-green coming out of the card and you need composite sync, then connect the green video line to both the sync input on the monitor and the green in. There are many entertaining permutations of this, but you get the idea. This will compromise the performance somewhat, but generally you can make this work by adjusting some of the magic trimpots in the display (the syncs and video levels come in at different voltages, which are being adjusted by the trimpots).

      But the tougher problem will be that the monitor may be designed for a fixed sync timing. That would not be changeable except via drastic measures. A multisync monitor sort of watches the syncs coming in and tries to make sense of them, but many older displays are designed to work at one setup. If this is the case, then you need to tweak the sync timing of the video card, which will be an adventure in software hacking.

      Pretty much all video cards are highly configurable in software with regard to sync timing. If you've used a control panel that shifted the raster around of the screen by software, it's simply changing the sync timing by shifting counter values. For lots of reasons, ranging from arcane hardware reasons to FCC compliance, the interface for changing timing is usually not public. But it is widely available to developers (some of whom most certainly are part of this community) finding the technical docs aren't that hard. I haven't made any attempt to look up the generic S3 driver in a Linux distribution, but there's probably a data table there that might do what you want it to do when poked with the appropriate number.

      It's challenging finding the right setup parameters. You basically are setting a group of countdown timers to generate the sync waveform, but video systems have very high bandwidth requirements so there are often issues with how you configure the video RAM so that you don't get conflicts when timings overlap.

      I guess I should start working on a sync tweaker! Issues like the ram array config, dot pitch of your display etc make it difficult for you to generally crank up an extra 100 pixels of width on the screen, but it's certainly possible.

      Enough already!

      David Fung

  8. LCD Controller's for laptops by Shadok8 · · Score: 1


    I've got a dead laptop with a good 800x600 Color LCD. You need to look into the Industrial PC Market. Controllers are out there, Typically the controllers are good for windows, no 3D, maybe multimedia capabilities. The bad part is they all seem to be expensive - I haven't bought one yet.

    I seem to have lost the bookmarks I had... There are quite a variety of decent sounding PCI controllers out there though, just start searching. You could also look into Industrial PC - small foot print single board computers (SBC's). You could have a decent but very small PC driving the display.

    Goodluck!

  9. Getting your hands dirty by gregbaker · · Score: 2
    Okay, I don't know much about hardware, but I'll try to get the ball rolling.

    Try opening up the laptop and have a look at where the display connects to the motherboard. It will probably be some kind of ribbon connector.

    Have a look and see if it is labelled in any way. If you're lucky, it will have each connector labelled with what it carries. Then, pick up a VGA connector--perhaps by getting an extension cable and beheading it.

    Finally, make the connections. The pinouts for a VGA connector can be found at: http:/ /www.geocities.com/SiliconValley/Haven/1236/pincon vid_vga_vesa_ddc.htm

    If the LCD connector doesn't have pinout listings, see if there is a number on it anywhere. Do a web search for that and see if anyone else has figured it out.

    1. Re:Getting your hands dirty by Anonymous Coward · · Score: 0

      VERY DANGEROUS...

      Basically, the overwhelming majority of LCD panels out in the world today are DIGITAL devices. VGA out is an ANALOG signal. In a nutshell, these are not compatable, and the process of digitizing a VGA signal for use with a flat panel is very tricky and quite costly (hardware wise) - you A/D section would need to be rated at least for 60 Mhz per color channel. Then there is the math to convert from your A/D's bit resolution to the panel's resolution. Then there is all the signal buffering that is needed.

      Yes, there are analog flat panels out there (raw devices, not LCD monitors). They are quite rare, especially for laptops. They also require a dotclock signal - something that simply does not exist on the standard VGA connector.

      If I had to guess, I would bet on destruction of the LCD if you were to try what you prescribed.

      If you want to 'try' something more interesting, either check out S3's web site or Chips & Technology's web site (no, I don't know their URL off the top of my head). They have chips that will directly drive LCD's. For Chips, look at the 65554, for S3, look at the 85c280.

  10. VNC DOS Port by Anonymous Coward · · Score: 2

    A xxx-DOS port of VNC _Has_ to exist somewhere, I mean, geez, I run a VNC Viewer off my Palm III!

    Try browsing through their "ports" page, everything form WinCE to PalmOS to Amiga to Mac to every Unix-ish system you can think of. I know there is a SVGA port that works, and, for that matter, all the other ports seem to work as well.

    Getting back to the Question at hand, as I recently helped someone out with a similar situation:

    First, pop open the display panel. If you're doing what I think you're doing, you won't need to worry much about the main unit.

    Next, after Zapping yourself with the high voltage PS from the backlight, ensure that all power cords and batteries are disconnected from the unit.

    Now, unscrew or pop a couple of clips to free the actual panel itself from it's mount in the panel housing. This (surprise, surprise) is the part you are most interested in. Find the manufacturer's name, and the part number on the back, and, you should be able to source an appropriate controller from that.

    Umm, and this is how far we've gotten so far. I have to ask James if Samsung got back to him this week yet. If not, I'm going to spend some time surfing for specs after my honeymoon with my wife. (umm, unless of course that priviledge is taken away from me tee hee!)

    Items of note:

    - That nice, bundled cable which connects the panel to the system contains (in many cases) _both_ display _and_ power lines.

    - Another thought we had was, instead of finding a single Card that would drive the display directly, we find the appropriate panel controller that accepts a 20Pin digital interface, then hook it up (via the 20 pin interface) to something like, ummmm, let's say, a Millennium 400 Max with LCD interface and... (smack)
    (Boy do I want one of those, but that is another thread all of it's own.)

    - You may be lucky and find out that the panel you are fondling allready is compatible with yonder 20 pin interface. Grab a connector, slap it on, cook up a PS for the panel, and away you go.

    FWIW: VNC Stands for Virtual Network Computing. The project was originally started as an operating environment for "Very Thin Clients", or, in other words, systems with _minimal_ capability. I think their first device was a wireless web tablet. The device itself was slow, but that didn't matter, because it was only being used as a graphical dumb terminal of sorts.

    FWIW2: VNC is based on XFree86, Check out the code, it's a pretty neat hack.

    Post a reply if you want me to e-mail you with any headway we make.

    YMMV, Enjoy.

    John Gunkel, (AKA Yanic, without cookie)
    Mad Scientist

    (come on baybe! moderate this puppy up!)

    1. Re:VNC DOS Port by dcbeard · · Score: 1

      From Beaurocrats-asleep-at-the-wheel Dept.

      John, loved your informative and humerous post, heellooo Mr/Mrs/Whatever moderator. This post is a =1 but certainly not the parent ;o)

  11. laptop displays on desktop by diadian · · Score: 1

    I have had quite a bit of experience with toshiba laptops and taking them apart. (Including the display)

    By running Linux on these machines (and machines by twinhead and texas instruments) I have found that usually these machines have modified video cards. (since the drivers that work for desktop versions hardly ever work on the laptop without some modifications to the XF86Config file).

    I also found that toshiba and TI are very tight lipped about the specifications for their display panels and about the modifications that they made to the cards and to the panel.

    In addition the connector that spans the gap from the lcd to the motherboard carries many more copper lines then a svga cable carries wires.

    So in other words, there is a reason for why those new flat displays have their own special connector and don't use VGA connectors anymore.

    Good luck anyway if you decide to try.

  12. Re: Crappy Laptop Processors... by Cheerio+Boy · · Score: 1

    True it IS fun but I'm just a freak about "underutilized" hardware.

    Although...Hmmm...fun IS a utilization....

    Forget what I said earlier! (Where's that damn soldering iron...)
    :)

    --

    "Bah!" - Dogbert
  13. LCD is NOT vga its digital my friend by johnjones · · Score: 1

    most infact if not all conections to LCD is done digitaly this is because of the way LCD work their are various standards for the conection

    at the moment thier is a battle on !!

    VESA used one conector with one way of tranfering signal

    industry used another

    the problem is that now we have huge monitors and the cable is the weak link

    the standard Digital conection method took time to get it to work right so people used their own method

    DO NOT SEVER THE CONECTION

    you may want to take it apart to fix it up so that you can plug your own keyboard and mouse in and ditch the laptops but keep everthing else intact

    these often have a trident vid card in and the X server is not bad 16bpp

    repackage it in a small box (of course in the colour of your choseing !! personaly I prefer the see thro with ligts inside)

    I have done this and I have written off 2 laptops do not make the same mistake as me !

    have a funky time

    john
    a poor student @ bournemouth uni in the UK (a deltic so please dont moan about spelling but the content)

  14. NT TSE by fchk · · Score: 1

    Use it as an XTerminal or as and RDP client for Windows NT Terminal server.

    I've had a look at NT Serminal server. It's really an X feeling - smooth and very useful if you must use M$ software - even on smaller machines.

  15. I'll chime in here... by Wirenut · · Score: 1

    Thanks for all the info.

    For those that commented about using them for Linux, x, etc. Good ideas, but I was more hoping for the ability to hang them on a wall, etc., to
    save space on my tech bench or where ever, in
    places where I don't need hi-res or 3d, but need to connect to a DOS or Win PC.

    Thanks again,

    Wirenut
    bwill@mcs.net
    www.bwill.net

    --
    "You're either outstanding, or outprocessing"
    1. Re:I'll chime in here... by technos · · Score: 1

      I used (for a time) a pair of NEC Versa laptops much in the same fashion. Snapped the display hinge off, then velcro'ed the newly flattened unit to the wall... After installing an ethernet card, internal null modem (Solder globs and wire) and Linux they worked great for 'Emergency terminals'
      (Had a simple C prog check for connect on the serial port, and if not, started X and VNC. I chose Linux because of the LOW memory footprint and the fact X could run the display at the highest resolution. Windows 3.11+32s would also work)

      There are quite a few ways to redirect a DOS console to the serial port, and VNC/Back Orifice both run reliably and speedily from a Windows desktop.

      Unfortunatly, if you were hoping to use the displays as monitors, forget it. If you really want to try, go out and find any Heath/Zenith 386. I'll send you the schematic.

      If you're just looking for a smallish monitor, I'd check out trade shows. I've had luck with the VGA units they use on FedEx boxes. (And at 7x9x9 and under three pounds, they'll fit on any bench, no matter how congested.) Plus they'll do 800x600 if you keep it under @63hz, and will probably only set you back a tenner.

      --
      .sig: Now legally binding!
  16. Use VNC! by Anonymous Coward · · Score: 0

    VNC (http://www.uk.research.att.com/vnc) is the thinnest of thin clients. The server does all the work, and the client can be quite dumb (much dumber than X). There are VNC servers and clients available for many OS's and processors.

    1. Re:Use VNC! by viking099 · · Score: 1

      While VNC is a possibility, I get the feeling that the computers wirenut works on aren't going to be set up to boot without a video out signal.
      then there's the problem of network connections and the client. if you really want to, all you would need to have is a box, sitting in a corner, with power and a networking cable running to it, and you never have to leave the desk. But VNC won't run with DOS, from what I've seen.
      VNC is not a bad idea as far as ease of use, but it DOES leave a rather nasty security hole in your system.

  17. Fixed-Frequency monitors by Zippy+the+Pinhead · · Score: 1

    Well, I'll bet you'll need a good FF video card. There are a number of companies who refit standard video cards to work with a variey of monitors. Mods include anything from changing the BIOS to rewiring the output circuitry to merely setting NVRAM settings in the card.

    An alternate method is to go dual-head with a cheal li'l 14" monitor on the primary and a G200 driving the 19".

    A search on Yahoo! for fixed-freq turned up a number of resources, including FAQs, lists of suppliers, monitor info and a circuit diagram or two.

  18. Sorry but.... by Manic+Miner · · Score: 1
    Sorry to say this but you are REALLY going to have your work cut out if you want to do this. As other people have pointed out there is a fundamental problem with an LCD pannel and that is that they are Digital, and a standard VGA signal is Analogue.

    This means that you are going to have to create a serious piece of custom hardware to connect them to a standard VGA output. The circuit would need to include a high speed Analogue to Digital converter, and a programmed proccessor chip to convert the digital signals into the correct format for controlling your particular display.

    You will need to be VERY handy with a soldering iron to manage all of the above but if you think you can, and can get the manufactures specs, then go for it. I will certainly be an interesting project! Having said this, my advice would have to be using linux as an X-Console, Microsoft terminal server, or some form of bought solution

    I hope this helps

    Manic.

    --
    If you ever drop your keys into a river of molten lava, let'em go, because, man, they're gone.
    1. Re:Sorry but.... by Manic+Miner · · Score: 1

      How about this for an alternative.
      Purchase a video capture PCMCIA card (if they exist) and connect the capture card up to the PC you want to connect the LCD display to..

      Run the software so that it is constantly updating a full screen image from the capture card.
      Extend the cable on the display, hide the laptop and PSU under a desk somewhere.. and hey presto, it looks like you have a fancy wall mounted LCD display, but in reality there is just some simple video capture and display software / hardware.

      Just another thought / alternative.

      --
      If you ever drop your keys into a river of molten lava, let'em go, because, man, they're gone.
  19. Use remote control by jsfetzik · · Score: 1

    Forget messing with the hardware and try a remote control app such as VNC(Virtual Network Computing) or PCAnywhere. I have used VNC to keep tabs on/control a machine on the other side of the building with an old 25MHz 486 and it worked out great.

  20. Here are some tips for you for doing this by Anonymous Coward · · Score: 0

    http://www.eio.com/lcdintro.htm

  21. Why not do it this way? by Anonymous Coward · · Score: 0

    Wait a minute! Why can't someone find a way to use the video card already installed in the laptop? When I opened up my old Toshiba 115CS, it had the LCD plug into a board that then plugged into the motherboard. This board had to be the video card, since it had a chip labled "CHiPs 65548" on it. Wouldn't it make our lives so much easier if we could just find a way to build an ISA/PCI interface to the laptop's pre-existing video card? If so, I'm interested! -Octorian http://www.rpi.edu/~konigd (AC, because I don't feel like digging up that cryptic password)

  22. Using an old LCD from a Laptop by ardinos · · Score: 1

    I'm building an MP3 player for my car and wanted an LCD display. I came upon the same idea of using an old laptop display. What you need to do is disassemble the laptop, scavenge the LCD, and buy a controller board. It will run around $200 for a PCI controller board and $50 for a connection kit. You look at the type of display and check the website, www.sageinc.com look at their board products and contact sales. I have a 166mhz pentium mmx with a 10.5" LCD hooked up that I'm encoding all my MP3's on and I haven't had any trouble at all with it. If you have any questions e-mail me at ardinos@yahoo.com

  23. Even more to the point: http://www.eio.com/sage.ht by Anonymous Coward · · Score: 0

    http://www.eio.com/sage.htm

  24. Controllers for laptop displays by jhutchins · · Score: 1

    The controller for the displays are usually imbedded in the motherboard, and there's no direct conversion that would let you connect a VGA/SVGA card BUT: It's possible that there would be a signal/cable correspondence between say a Toshiba laptop display and a Toshiaba flat-panel monitor. See if you can find some specs on the adaptor and cable for one of those. It may be that there's enough other stuff in the flat panel box that you're not saving anything with the laptop screen, but it's worth looking at (so to speak).

  25. Great Info, thanks! by Wirenut · · Score: 1

    Those two sites above have exactly what I needed, the contollers are a little pricey, but will what do I want. Thanks. wn

    --
    "You're either outstanding, or outprocessing"
    1. Re:Great Info, thanks! by joshwa · · Score: 1

      I couldn't find pricing information anywhere on the site... could someone point me in the direction of a price list for the controller boards?