Inside the Atari 1040STf

Atari's first member of the ST line, the 520ST, relied on both an external power supply and a floppy drive. The 1040STf, shown here, integrated those two components into one case and upped the RAM to 1MB, launching for $999 in 1986 as a complete system with a base unit, a monochrome monitor, and a mouse.

The ST series ran a windowing system known as GEM (Graphical Environment Manager), developed by Digital Research. That, in turn, ran on top of an operating system called TOS (Total Operating System). But, as with a Mac, the user saw only a friendly graphical desktop--no command line here.

Just as the Macintosh platform quickly dominated the world of graphic design, the Atari ST found its strongest niche in music production. That's because Atari included two built-in MIDI ports with every ST shipped--a world first for mainstream PCs at the time.

MIDI allows electronic musical instruments to control one another, which meant that the ST could capture a performance, play it back, or generate a new one from scratch. Atari ST machines saw widespread use for audio-production work well into the late 1990s due to their stability and their excellent music software. A few studios still swear by them today.

Atari never fully utilized the ST's cartridge port (shown here), but third-party developers sometimes used it as a hardware expansion interface.

The 1040STf shipped with a double-density, 720KB, 3.5-inch disk drive that--thanks to the similarities between the ST's underlying TOS operating system and MS-DOS--could read (but not write) IBM-format disks.

The last letter in the 1040STf name stands for "floppy," denoting the fact that the system shipped with a built-in floppy disk drive. Its predecessor, the 520ST, used an externally attached, 360KB, 3.5-inch floppy drive that increased cable clutter.

The 1040STf came equipped with an array of expansion ports along its right rear side. From left to right: a serial port (for use with modems), a parallel printer port, a hard-disk port, and an external-floppy-drive port (for a second floppy drive). The hard-disk port used the proprietary ACSI interface, an Atari-developed derivative of the common SCSI standard.

Now it's time to take this beast apart. Here, I've flipped the machine over, exposing its underside, which seems just as stylish as the top of the unit. In the process, I've revealed a curiously shaped recess in the lower-left corner of the machine. Let's take a closer look.

Within the secret alcove located on the bottom of the unit, we find two DE-9 connectors--one labeled with a joystick icon, and another with both a joystick and a mouse.

This design proved extremely inconvenient for two-player gaming. Initially the user needed a mouse to run most game programs, so the mouse had to be plugged in. To have two joysticks attached simultaneously, the user had to prop up the machine along its back side (which strained all of the connectors in the back of the machine) and awkwardly exchange the mouse plug with a joystick plug, by touch. Not fun.

Here I've removed the top half of the plastic case, revealing the inner goodness of the 1040STf for your amusement.

With the keyboard set aside, you can see that Atari encased nearly every internal component of the computer in sheet metal, a technique called RF shielding. It blocks emissions that radiate from the ST's circuitry. When electricity flows through a conductor, it generates radio waves that can disrupt commercial television or radio reception. The Federal Communications Commission strictly regulates devices that might interfere with broadcast media, requiring gadget designers to block these undesirable signals with metal shields.

I've now unplugged the keyboard from the motherboard and removed the entire assembly from its natural place, setting it aside. Here, I've also removed a few keycaps to show you how they attach to the underlying keyboard assembly.

The 1040STf's keyboard was never very popular due to its mushy feel, but users appreciated its layout for its similarity to the widely imitated IBM PC AT keyboard.

Here's an under-the-hood peek at the back of the Atari ST keyboard assembly. This is also an opportunity to take a closer look at the mouse/joystick ports I mentioned earlier, which are built directly into the bottom of the keyboard assembly.

It's time to start dealing with the RF shielding. First, I've detached a shiny portion of the RF shield to expose an area in the left interior. That's the computer's power supply assembly, which Atari cleverly designed to be easily replaceable for service.

After I remove three more screws from the bottom of the unit, the 1040STf gives up its floppy-drive unit, shown sitting on the desk behind the computer.

I've now removed the motherboard (still encased in shielding) and the power supply from the system's plastic housing, which looks on longingly from the background.

You'll notice that the shielding is far from clean, which means that I'm not the first one to take this unit apart. Fingerprints and smudges left on the shielding rust or discolor the metal over the years. Other clues of entry include stripped, mismatched, or missing screws--all of which this machine has in abundance. Someone has definitely opened this computer multiple times, likely for repairs.

As you've seen, metal shielding encases the entire motherboard. To remove the shielding, I need to twist small metal tabs that hold the two halves together. The manufacturing process had slipped the tabs through prestamped holes in the shielding and bent them into a shape to ensure that they no longer fit through the holes.

Why did the makers do this? It's cheaper than using screws. A company can stamp a form out of sheet metal, bend it to shape, and fasten it together with no extra parts required.

With the RF shield and power supply removed, we finally get our first full view of the Atari 1040STf's motherboard. Immediately, you'll notice a small metal box near the center of the motherboard--even more RF shielding! This is beginning to look like a Russian nesting doll. We'll take a closer look at that mysterious metal box in a second.

The Atari 1040STf was the first sub-$1000 computer to include 1MB (1024KB) of RAM. And here it is. Those two rows of small black chips (32KB per chip) take up quite a bit of real estate.

In addition, the six large rectangles toward the top center of the image are ROM chips that contain the ST's built-in operating system software.

The trained eye also notices an empty space in the upper-right corner. That's reserved for an RF modulator, a device that allows a user to hook the ST to a regular TV set. Atari also shipped configurations of the ST line (the 1040STfm, for one) with a modulator in place.

Remember the small metal box on the motherboard I mentioned earlier? Here, I've opened it to reveal the ST's "video shifter" chip (the large black rectangle near the center of the image). This chip is responsible for generating the ST's display output. It apparently emits more radiation than usual, since Atari needed to encase it in extra RF shielding to gain FCC approval.

Examining the right rear corner of the motherboard brings us to the heart of the ST. An 8MHz Motorola 68000 (in this case, manufactured by Signetics) serves as the Atari 1040STf's CPU. The 68000 is a 32-bit CPU with a 16-bit bus, a fact that Atari drew on when naming its newest computer line--"ST" for "sixteen/thirty-two." Weird, I know, but it's the truth.

In this cluster of important chips, you can also see the Yamaha YM2149 Programmable Sound Generator, an audio synthesizer chip that provides the 1040STf with music and sound effects. Other companies used variations of this chip in home computers and video game systems, as well.

Though the ST sold particularly well in Europe, the line never took off in the United States. Macs and cheap PC clones largely overshadowed Atari's mighty mite. Atari followed up the 1040STf with enhanced machines such as the Mega ST, the 1040Ste, and even fully 32-bit computers like the TT030 and Falcon030 in the early 1990s, but none had the impact that Atari would have liked. Aside from being a superb line of gaming machines, the ST series left us with a lasting legacy of glorious music. If you wander into a used musical equipment store, don't be surprised if you see an old ST sitting in a corner somewhere, still chugging along.

Can't get enough old-school tech teardowns? Check out some of my other workbench adventures:

* Atari 800

* Commodore 64

* Nintendo Family Computer, aka Famicom