Project: Fallout Terminal

Okay, the name isn't a reference to anything in particular, but a description that somehow sounds cooler than it may be. It's going to be a basic Linux system that hooks into a terminal server, and it's being housed in a surplus US Civil Defense CDV-715 Radiation Fallout Meter. Despite what many think, this model is not a geiger counter. Its made for use after the nukes fall and to read the level of fallout. Basically, if you need to use one of these you're probably going to die pretty soon. For the collector types, I only use damaged or broken meters for my projects. I won't pay the price for a working one, and have managed to build up a nice stash of bad ones.

First off, if this seems familiar, you may have seen a few of the other mods I've done using these meters. For the past few years I've been modding them into USB, firewire, and now eSATA 3.5" hard drive enclosures. Most have gone to friends and family, but there are a few extras that have made it into the wild.

I've also built two PCs in these cases using embedded 3.5" boards. One is a Pentium-M 1.8GHz, the other a Via C3@667MHz. Never really used either of them, the Pentium-M was too loud and the C3 had power issues. Well, I stole the PSU from it for another project so it's been boxed up until I get around to wiring it back together. I still have both, and while they'd work fine for what I'm doing, I'd rather have a much lower power system built for the purpose.

Anyway, on to the hardware...

For this project, I'll be using another embedded 3.5" form factor motherboard. This time it will be an Advantech PCM-5825. This uses a NationalSemi GeodeGX1 CPU@300MHz. Performance is equivalent to a PentiumMMX@~200MHz. It's descended from the old Cyrix MediaGX and is a kind of half-breed 486/586 core with onboard audio and video that rely heavily on the CPU. It's weak, but for what I'm doing it should be fine. It helps that this CPU(now owned by AMD) is used by Wyse in a lot of their Winterm models, so I know it will work for a terminal setup. There are updated versions of the CPU/chipset that increase clockspeed and add DDR support as well as more USB and even SATA on some versions. The base core is still the same.

So it's a poor performer, why would I use it? This board, running from a 45 watt PSU, pulls between 6-7 watts idling in the BIOS and requires about zero effort for cooling.

And a quick word on the 3.5" embedded form factor, since someone will ask eventually. The board size is 105mm x 145mm, same as a 3.5" hard drive. They're available with CPUs ranging from the 386 up to 800MHz bus mobile Core 2 Duos@2.6GHz. I've also seen them using xScale and other non-x86 CPUs, and recently saw there'll be one based on the Intel Atom. I like the form factor a lot, but they're hard to find and not cheap unless you buy used. Oh yeah, there's also an identically sized embedded form factor called ECX which is backed by Intel. Only real difference is ECX has a "standardized" PCI-e/USB/PCI expansion bus and most E3.5 use PC/104, PCI/104, and/or mini-PCI.

And finally, pics of the victims.

The board.

Bottom. Currently only have 128MB of ram, need to get it running and see if I need more. I also plan on running the whole works of a compact flash card. I've got a few different ones to play with, hopefully the board will play nice.

The unmolested case.

The guts.

Guts removed. I'll be cutting the "legs" off for clearance.

The gauge will show drive activity even though there won't be much when it's being used on the terminal server.

And I've started my layout for the ports.

For the ports, I have a method that works pretty well. Consists of a drill, an old slot bracket, files, and a lot of arm motion. The big issue will be keeping things lined up. Get one port finished, then start another, constantly checking alignment. Consider there are 7 holes on this one, and I've got a challenge.

I'm also going to have to find cables for USB and audio as well as plan how I'm going to power the unit. It will run off a single 5 volt source, but the standard power mode is AT. It does have an ATX mode, but it's designed to be run with a real ATX PSU. I could use a PicoPSU and custom cables, but that's more money to spend and more chance of complications. I'd like to get the ATX mode working, but it's not really that big a deal if I can't. With 7 watts power use I could just leave it running all the time.


And a little update for today.

First up, a pictorial of how I do ports.

Step one, after layout, drill two holes, then using screws and nuts affix the serial port slot bracket to the case to be cut.

Step two, drill a bunch of holes to remove material.

Step three, file like a madman using the slot bracket as a guide. The case is aluminum and the bracket is steel, so using a light touch means the files won't dig into the steel once you hit the edge and you should get a very nice port.

Step four, ogle your well shaped port.

About an hour and a half later, I had both VGA and serial openings complete as well as ones for the network jack and LEDs, and on the far right the hole for the reset button.

I still need to do the opening for the PS/2 port, then start wiring up the USB and audio cables. Power will be last, have some things to test in regards to the ATX mode.

I'm contemplating adding a USB hub since the board only has two ports, but with the onboard only being USB1.1 it's sort of pointless. I'll save that for the next one I build. Yes, there'll be another one being done when I finish this. I've got another Via C3 board that will be the basis for a system to run a 10 year old guitar MIDI interface.


Little pic of how well the 3.5" embedded form factor fits into these cases. Snug, but lots of room on the ends for passing cables between the top of the board and bottom of the case.

Got the PS/2 port done but no pics yet. Also stuck on some rubber feet I had left over from a HD case build. This one doesn't really need them as it won't have a fan on the bottom, but there will be some holes put in for airflow.

Right now I'm waiting for USB and audio cables. Found a set of the original cables, which will make things much easier since the board uses a narrower pitch on the pin headers than a standard board. The USB cable will be unmodified, but I'll have to change the audio cable to use different jacks.

I've decided I'm not going to bother with ATX mode for power, I'll save that for the next one. Much easier wiring and it lets me get this done a bit quicker.

And one of these days I have to work on the wiring for the gauge.


The scratches on the interior are a result of deburring the inside of the ports after drilling and filing. I'm not too concerned about that, hopefully once I have everything inside I'll never have to open it back up.

I've considered polishing the outside of one of these cases, but I don't have the patience to do it properly. I may paint one of the spare cases I have that's in bad condition, but that's a project for another day.

Got my USB and audio cables today. Going to get the USB ports done tonight or tomorrow, then I'll start messing with the audio cables. I'm actually stealing an audio cable from another board, then swapping part of the cable onto the socket from the cable set for this board. The other board is another Geode board that was deemed "meh" due to a poor layout. It'll eventually get used for something, and then I'll have to make another audio cable for that one. Or I'll sell it and let the next guy worry about it. Would be a lot easier if they used standard pitch pin headers.

And pics, because I took some.

The bag of cables

what I'm actually using

And a shot showing the PS/2 port and rubber feet

And if anyone wonders, that's a sheet of ~2mm orange UV-proof plastic as a work surface. I got it when I bought an LCD; the seller used it to protect the screen in shipment. Fits perfectly inside of a drawer on my desk and is at the perfect height for working on projects while sitting in my computer chair.


And one new pic, got the USB ports 99% done. Need to pull things apart and fine tune things a tiny bit

Now I need to make a trip for parts, so I probably won't have any new pics or updates until this weekend. I need to pick up some stereo jacks for the audio and I want to see what I can find for a power switch. I have a toggle in my parts box, but it's a bit larger than what I wanted. I'd love to find a rotary switch that will fit the spot where the original power switch was, but so far they're all too large.


Got a little more done today. Got up, ate something, then took a run to Radio Shack to spend too much for parts that I didn't feel like ordering online. I'll get to some of those in a few.

First, need to back to some earlier shots of the top of the case. If you look here, you can kind of see the raised sections where the original power/level select knob and the zeroing knobs were.

A few better pics of those areas.

Had to take about a half hour today to clean that up for some other components to fit, as well as cut the legs off for better clearance. Here's a few new pics to see what has been done.

Hmmm, what's in those spots now? That big one looks like a switch, but what's the second? Maybe a few more pics will help.

Yep, managed to find a rotary switch to use for power, and put a power jack into the area where the zero knob was. Wasn't really what I wanted, but for ease of wiring it was better to put the power jack on the same part the switch was on. If not, I would have ended up with more wiring to stick into the case as well as tied them all together. Wouldn't be simple to even get it together if the jack was on the lower part.

Started cutting and placing wires, soldering will be done tomorrow when I also deal with these.

Line in and out only, maybe I'll throw on a jack for the mic. Interesting thing, the board also has powered, albeit very low power, speaker out headers. Not going to use them, but I was tempted to put a pair of RCA outs onto the case for those.


Little bit of an update here. Didn't get around to soldering things until tonight, and only got the power and power LED done, but happily everything is working. I'm actually using a 5 volt, 2.1amp wall wart for power right now. This thing uses so little power it's creepy. I'll have to move up to a larger one for the software install, my USB CD drive uses almost as much power as the full system.

And pics...

First, the semi complete wiring for the top half. Still need to get the wiring done for the meter. Power molex goes to the board, and I need to add headers for the HD activity to the board where it used to have an HD activity LED.

And power hooked up, off.

And power hooked up, on.

And power hooked up, on, flash off.


And an update for May 17th. Got the audio jacks soldered and installed.

Just Line-In and Line-Out right now, I don't really need the mic hookup on this one.

In the process of installing Windows 98. Just want to get it running something while I work on the "real" software install. Found some issues to deal with.
- It does not boot from USB at all, so I had to hook up a CD drive to the onboard IDE
- With a slimline DVD drive, the 10 watt wall wart didn't have enough juice to copy files from the CD to the compact flash card. System kept rebooting.

I was able to boot off the CD, then fdisk and format the flash card. But then I had to shut down and copy the installation cabs over using another PC. So far so good. Starts, boots off the flash card, and I'm about halfway through the 98 installation. Slow, but the flash card I'm using is also very slow. Once 98 is installed, I'm going to do some performance testing, then probably clone the flash card onto a faster one and see if that makes a difference. The next step will probably be to install Win2K, just to see if it makes a negative difference. Rumor is it may run better, but we'll see. Eventually I'll throw together an embedded or stripped down XP install, depending on what drivers I can find. I know the audio drives are iffy at best under XP. From there I'll probably start messing with flavors of Linux, find what gives the best performance for the thin client and basic browsing tasks while still supporting all the hardware. That's the tough part right now, the MediaGX/Geode platform has had three different owners and none of them did much in the way of support.

Oh yeah, got the HD activity circuit wired up, too. At first I thought it wasn't working, but after getting everything put back together the needle started twitching with any access of the flash card. Creepy thing is that the ONLY noise this box makes is the needle moving. There are no other moving parts, and the casing muffles or blocks any component squeals that might occur. I'll get some video of the needle bouncing one of these days, but feel free to enjoy these videos from my HD cases and a remote power/reset console I built a few months back.

Videos of meter needles showing HD activity

Original firewire HD case USB 2.0 HD case Original transferring to USB HD case Control Console


And I'm calling this one complete, so here are the final photos as well as a video.

Still fighting with the software side, but that's pretty uninteresting stuff. Maybe I'll snap a few more pics when I get this on the terminal server, we'll see. I do have matching peripherals from the Pentium-M system I built a few years back, so that might be interesting to see it all in action.

Anyway, onto the pictures.

The boring front side

The back side with ports


And the video. 1 minute, ~4MB, with sound so you have an idea of what noise it doesn't make. There's some background noise from a ceiling fan and two other running PCs, but the only noise this system makes comes from the needle and the onboard speaker. Well, maybe the switch if you want to count that. Video is power plug in, power on, then booting until the time it crashes during the boot of Windows 2000, then shutting it back off.

Click me for WMV video