From Cop Car Data Terminal, To Retro Computer

It is possible that you will have lived your life without ever coming into contact with a Motorola MDT9100-T. The data terminal of choice for use in police cars across the globe was a computer with a full-sized QWERTY keyboard, a small CRT display, a mainboard sporting an Intel 386SX processor, and a custom version of Windows 3.1. [Trammell Hudson] and some friends from NYC Resistor scored some MDT9100s in an online auction and found them to be just too good an opportunity not to crack them open and see what could be done.

The custom Windows install could be bypassed with a DOS prompt for some period demoscene action, but [Trammell] wanted more. The 386SX wasn’t even quick when it was new, and this computer deserved the power of a BeagleBone! A custom cape was created on a prototyping cape to interface with the MDT9100 header carrying both keyboard and video. A bit of detective work revealed the display to be a 640×480 pixel mono VGA. The ‘Bone’s LVDS output can drive VGA through a resistor ladder DAC with the aid of an appropriate device tree overlay. The keyboard was then taken care of with a Teensy working as a USB device, resulting in a working Linux computer in the shell of an MDT9100.

It’s always good to see old technology brought up to date. Amusingly a couple of years ago we reported on the death of VGA, but retro projects like this one mean it’ll be a long time before we’ve heard the last of it.

39 thoughts on “From Cop Car Data Terminal, To Retro Computer

    1. If I ever design my own devboard or SBC, I’ll name all daughter/expansion boards butt plugs in hope that one day there will be a HaD article titled “Collection of butt plugs to fulfill every hackers’ needs!”…

    2. They’re *not* the same thing. They’re the same “kind* of thing, but they are completely incompatible. The last thing you want when looking for an add-on for your Beaglebone is to wade through all the Pi and Arduino peripherals that are completely useless to you!

      Shields are for arduinos.
      Hats are for Pi’s.
      Capes are for Beaglebones.

      It’s silly to complain about it.

      1. oh… I always thought that shields were for Captain America, capes for superman and hats were something my both my grandfathers used (they are my personal superheroes). So now I’m confused. I wonder what will be next?

        btw “silly to complain?” the names are silly and confusing, what was wrong with naming expansions and add-ons with a combination of a few letters and some numbers. Then it was clear what the newer version was. If the items were related the numbers would look like they were from the same family.
        But then again, what can you expect if the main-board (the board it all connects to) is called Raspberry pi, beaglebone and arduino. As soon as they realize that names will eventually run out (i.o.w. the names are getting to silly) the numbering scheme will be back in fashion. Just hang on.

        Then again. the power of these names is to make technical stuff appealing (or to be more precise, less scary) to non technical people. Eventually drawing more people into realm of this technology. If it wasn’t for these silly names, it might have never caught on.

        Can’t wait to see the name for the next kind of board. At an insanely low price and high computing power at the expense of only a few mW. It can perhaps only be named KittenPower. With the addons being called, KittenPaw, KittenClaw, KittenTail and the wireless addons being called KittenMiauw and KittyCry. Then finally the enclosures being made for it could be called KittenBox and the larger ones to holds all the expansions CatBox.

        The future will be bright.

        1. As long as it distinguishes itself from other similar devices, and is internally consistent (this is important), I don’t see what your big fucking issue is with the naming scheme. “Oh no they use words instead of letters OH GOD.”

          In all honesty, get over yourself.

        2. Are the terms “motherboard” and “daughterboard” sexist or misogynist? I haven’t located a millennial (at least not one who cares about things like “microaggressions”) to ask…

      2. “X specific add-ons” would be less pretentious and more factual, where “X” is the name of the main device.
        But it’s all done because some marketing schmucks wants to establish a brand and have that be the selling pitch, instead of the device’s price, quality and specifications.

      3. They are almost the same thing. Any decent hacker could adapt an Arduino shield to a Beaglebone or PI and the other way around if it’s electrically/speed compatible just by rewiring signals and porting drivers; it’s just ones and zeroes. Those (shield, hat, cape, etc) are commercial names producers stick to almost generic things to make people associate with a brand even when they hear about them in totally different contexts. How many times the Arduino came to mind as you heard someone talking about a shield? That is done on purpose.
        The complains are sound: every hardware producer now must stick a different name to an expansion board because other names became distinctive elements of other brands, and I don’t think we have enough names of stuff that connects to other stuff for every hardware producer out there, so pretty soon either they adapt to names already used (==confusion) or they start using more and more meaningless names (==confusion). After socks, gloves, hoods, scarves, we will likely see glasses, umbrellas, skis, ties etc. What about Arduino/Beagleboard/RPi/etc. extension (or daughtercard, addon etc.) instead? Chances are that if you ask an electronics shop clerk for a shield without mentioning the Arduino he will point you to the next Marvel merchandise shop down the street, so I’d get rid of those unneded names in favor of a generic one preceded by the board it applies to.
        Using different names for very similar things just because they stick to different other things would be like using different names for tires if they’re for a Mercedes or a Honda, the world has adapted to simple and extremely understandable terms like “Mercedes tires” or “Honda tires” for a reason.

        1. Overloading of old names as it were is nothing new. There are plenty of stories about someone having asked for a light bulb at a gas station and being told to go look in the shelf of vegetables… since gas stations have changed from being service-stations of sorts with a limited range of spare parts, to convenience stores that happen to also sell gasoline. Now Mercedes and Toyota and the others never needed to market their various add-ons and spare parts under different term names. Oil filters and suchlike has always been different for different makes and models. However, when it comes to the microcontrollers and small computers, it is quite convenient that they use different distinct terms for the add-on boards (Capes, HATs, Shields, POTs and so on) so that when considering purchasing one, the question of whether it will be compatible with the present device, will be answered right away. And silly names on things have never stopped anyone, but in choosing between levels of confusion from re-defining old terms, or inventing new ones, I’d prefer the less confusion of the new terms. The context easily makes it clear that we are not referring to apparel, even if simultanesouly concerned with cosplay or wearable computers.

      4. The raspberry Pi HAT spec was a mess. it included an I2C eprom that only had a single address. leading board makers to include a disable jumper for stacking plus the 40 pin header changed a lot since the early models, so to make a compatable hat for all versions you’re pretty constrained. I predict they’ll throw it out and re-do it from scratch sooner or later, which probably means replacing the 40 pin with something else to destinguish new spec from the old.

  1. Another rip everything out and put a proto board in it because nobody can RE hack.. That 386 board had NO security you just had to learn to overwrite a volume pointed to by a bootrom or MBR.. Likely SPI or RS232 or even ATA or compact flash..

  2. Nice.
    How about building it into a regular car and programming a contorted kind of infotainment into it. Could type in the song you want to have it play and read out ome OBD data :)

  3. I agree wit xorpunk – ripping out & replacing the guts isn’t hacking, it’s taxidermy. The 386SX-16 was powerful enough to run full-blown AT&T UNIX and host both i860 RISC and Intel iPSC supercomputer simulator. Still got one in my loft.

      1. I was a fan of the SX for bang for buck. I liked old windoze because of compartmentalization… as compared w new bloated integrated versions. Love windoze? Not so v much, but it had some support and ancilliaries.

        It behooves one to qualify bashes at least so you don’t become thought of as, an “F” in editorializing. I almost responded merely with “-1,” and realized I would be as you if I did not distance myself from the practice of posting simple bashes. Hopefully, editors will again remove my post, which is required by the HaD System, when it removes the offending post which induced my responce. But maybe you are just having a bad hair day.

    1. I don’t, at least not fully. Taxidermy isn’t a bad phrase here, but you certainly have put a negative spin on it. The ‘hack’ here is interfacing a beaglebone with the keyboard and VGA display and then shoe horning it all into the original case. Nothing groundbreaking or earth shattering, but still a hack. Credit where credit is due.

      Repurposing an old 386 is all well and good until you want to actually do anything with it. I have a ton of vintage 386 systems, but I don’t make any claims that they are useful general purpose machines, or even that much fun to use, in todays day. A modern embedded Linux system is infinitely more useful than an extremely dated 386 embedded system. I my head, it all comes down to the software the system can run. Old 386 w/ limited resources? Not much. Modern system? Way more. Sometimes that’s the point. See what you can do with limited resources

      Depending on your needs for the device, replacing the old 25MHz 386 with 4MB of RAM with a modern 1GHz ARM with 512MB + gobs of storage and network options may be much more appropriate.

      I would have liked to see some more about the original system and all of it’s embedded back doors and tweaks, but really, that old 386 is pretty hobbled. It also doesn’t look like it’s especially got any storage expansion, looks like just a few MB of soldered-on FLASH, two RS233 ports, and a 16-bit PCMCIA expansion slot. Enough to do some things, but not enough to handle any modern workloads. Might be able to boot a linux kernel and NFS the rest, but probably not much more than that.

  4. Motherboards and daughter boards et al, assembled under one roof, if well weaponised whether with actual weapons or merely info abilities, becomes, one bad boy. Like HAL, if you will. Hats capes etc are just like SOS in a cafe. Bored folks re-name stuff. Hat describes an upper shield versus somethig else if there is a bottom shield. It can help specify in short-speak, or add humor to reduce boredom which can reduce ‘mis-hearing.’ “Two men on a raft.” Discern, gentlemen and others. Discern.

  5. Used to configure/maintain these units. They are examples of the engineering build quality that Motorola produced (now Motorola Solutions , after the company split into different groups). These units operated on private LMR channels. The chassis of the MDT had a radio attached to it. There were other elements on the fixed end side of the network that would be needed to make it work.

    Unfortunately, the links (at the time) were not encrypted. Bill Cheek was able to decode the MDT data streams (leading to all kinds of legal problems he stirred up).

    There were earlier variations. The KDT-480 for one.

    What led to the demise of this product was the cheap availability of ruggedized laptops and the requirements for encrypted data, and more functional software applications that ran on said laptops (over commercial networks vs. an agency having to build out a separate repeater – at the time an MSF5000 or Quantar, to support data).

    I threw a bunch of them out of the garage into the scrap heap last year.
    Just taking up space. No real value to someone who works on such things everyday.

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