Atari's Answer to the Apple II
Thirty years ago this fall, video game pioneer Atari released its first two entrants in the home-computer market: the Atari 800 and 400 computers. Originally retailing for $1000, the Atari 800 shipped with 8KB of RAM, upgradable to 48KB. Its little brother, the Atari 400, was priced at $550. The Atari 800 began as a next-generation follow-up to Atari's groundbreaking Atari 2600 video game console. Upon seeing Apple's success in the early personal computer market, Atari executives ordered their engineers to turn the new hardware into a personal computer system, which became the 800. To celebrate this anniversary, let's peek inside this classic machine to examine its advantages and drawbacks.
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Meet the Atari 800--my family's original Atari 800, in fact. My father bought this machine in 1980 or 1981, and my older brother learned to program BASIC on it when he was very young. The same story played out with countless other low-cost home computers throughout the world, inspiring a generation of kids to become computer programmers.
Scattered to the left and to the right of the Atari 800 are software cartridges. They plug into the system and give the user instant access to software without loading delays. The 800 could also use the 410 Program Recorder (a slow cassette-tape drive) or the 810 Disk Drive for mass data storage; both of them plugged into an external peripheral port.
Left Cartridge or Right Cartridge?
Here we see a close-up of the BASIC programming language cartridge sitting in the Atari 800's left cartridge slot. The 800 also had a right cartridge slot, but this slot received very little use throughout the system's run. The original purpose of the right cartridge slot was simply to extend the functionality of a cartridge plugged into the left slot. Joe Decuir, one of the 800's designers, says, "We envisioned being able to have a mother cartridge and extensions of that mother cartridge. It never happened."
Only a handful of commercial cartridges--mostly programming utilities--used the right slot, whereas all primary cartridge software used the left slot. Subsequent versions of the Atari 8-bit computer line omitted the right cartridge slot altogether.
One groundbreaking (but regrettably underutilized) feature of the Atari 800 was its four joystick ports, arrayed along the front edge of the unit. With analog paddle controllers (two attached to each port) in place, the 800 could host an eight-player game (as in Super Breakout). By far, the best game to use all four ports was the strategy game M.U.L.E., one of our "Ten Greatest PC Games Ever."
The Atari 800's expansion options were limited. Atari avoided an Apple II-style internal card bus, instead relying on an external serial port for peripheral expansion; access to this port was through a 13-pin connector on the side of the unit.
A limited number of peripherals (including disk drives, printers, and modems) could be daisychained together through this port. Though this serial-based expansion method was reasonably user-friendly, it suffered from slow speeds and large tangles of cords.
A Little off the Top
Internal expansion on the Atari 800 was limited to the four internal card slots shown above, positioned beneath a removable panel above the cartridge ports. Atari sold user-friendly "Memory Modules" (available in 8KB and 16KB sizes) that could be inserted and configured to a maximum RAM capacity of 48KB in three slots. The slot closest to the keyboard was always reserved for 10KB of ROM containing the simple but necessary Atari operating system.
Now we're ready to take this beast apart. Upon flipping the 800 over, we notice that the computer's stylish form extends even to the bottom of the case, which was designed by Atari employee Kevin McKinsey. A plain white label identifies the model number and the serial number (inset)- somewhat worse for wear after decades of being scuffed. Only five screws separate us from the 800's glorious innards.
Cleft in Twain
Its eight retaining crews removed, the 800 comes apart in two halves: the upper part (face down and with the keyboard still attached) is shown at left; and the bottom part (right side up) is on the right. The smaller piece sitting behind the two halves is the removable RAM compartment access cover, seen earlier.
Here, the 800's keyboard sits detached from its rightful place for the first time in three decades. We also see the memory access cover (above left), with spring-loaded cartridge door attached.
The yellow keys on the right (labeled 'Start', 'Select', 'Option', and 'System Reset') are merely moving keycaps that snap into the upper half of the case; their functional switches reside in the bottom half of the 800.
The Bottom Half
What you see here is slightly deceptive: The guts sitting on the bottom half of the unit actually screw into the underside of the top half. Here, they're simply resting where they'd normally sit in the assembled unit.
Within the case lie two basic components: the motherboard, currently covered with a thick aluminum RF shield (more on that in a moment); and the power board, which plugs into the motherboard. Also visible is the unit's speaker (the round thing at lower left); when the machine is properly assembled, the speaker emits a somewhat annoying click sound whenever a keyboard key is pressed.
The Power Board up Close
The motherboard (left) and the power supply board (right) link together vertically via a large multipin connector. On the power board sit the four switches that rest beneath the yellow Start/Option keys (mentioned earlier) in the top half of the case.
The main keyboard connects to the motherboard via the wide multipin connector near the front of the unit, close to the joystick ports.
A Tale of Two Boards
In this shot, I've separated the power board (right) from the motherboard (left); the latter is still encased in its massive metal shielding. The engineer who designed the shielding cleverly cast it into a functional structural shape that defines the cartridge and the memory slots.
The power board receives power through the previously seen power-in jack. It then conditions, regulates, and adjusts the electricity to the voltages required for various parts of the system.
Cracking the Shell
Here, I've flipped the motherboard/RF shield assembly over and have partly disassembled it to expose the motherboard. This thing is built like a tank. The Federal Communications Commission gave Atari a hard time about the 800's electromagnetic emissions (attributable to its inclusion of an RF modulator, a device that outputs a TV video signal), so Atari encased most of the 800's functional guts in thick metal shielding. More on that in the next slide.
Nolan Bushnell (founder of Atari) commented on this subject during when I interviewed him a few years ago.
A Knight Without Armor
The big metal thing you see to the left is a 2mm-thick RF (radio frequency) shield designed to block unwanted radio interference emanating from the Atari 800's circuitry. When electricity flows through a conductor, it generates radio waves that can disrupt commercial television or radio reception. The FCC strictly regulates devices that might interfere with broadcast media, requiring gadget designers to block these undesirable signals with metal shields.
The Atari 800 also contains an 'RF modulator'--a component that converts the computer's video output into a signal that can be transmitted (via a cable) to a TV's antenna jack. Because RF modulators radiate signals that may interfere with TV reception, the FCC mandates that they be heavily shielded.
Now that the shield is off, two major parts of the motherboard assembly are visible: a molded plastic cage (left) designed to guide cartridges and Memory Modules into place, and the motherboard itself. The plastic cage usually sits on top of the motherboard (as shown in the previous picture), but I've removed it and set it aside in this shot. The vertical card plugged into the rear of the motherboard is the CPU card, which we'll see more of in a moment.
The Brains Behind the Whole Operation
Here we get a close-up look at the CPU card. The Atari 800 uses an 8-bit Synertek 6502B microprocessor, a variant of the famous and prolific MOS 6502.
You might notice a sticker labeled 'GTIA 1/16/86'. That's the date when my father upgraded our Atari 800's television adapter chip--the CTIA--to the improved and revised GTIA. To the left of that sticker is the ANTIC chip, which works with the CTIA/GTIA to create the Atari 800's impressive graphics. The 800 also contains a custom sound chip--POKEY--that provided excellent music-reproduction capabilities for 1979. Overall, the biggest advantage that the Atari 800 had over its competitors was its powerful custom chipset, though that wasn't enough to guarantee Atari a prime spot in the personal computer market.
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