Inside the Commodore 64

First, though, let's zoom in on a few features on the outside of the box. Looking at the right side of the C64, we see the most commonly used ports on the computer. Two connectors labeled "control port" support Atari-compatible joysticks. The "on" switch is self-explanatory, and an external power supply plugs into the seven-pin DIN connector to the right.

A row of unlabeled ports spans the back end of the C64. From left to right, we see the cartridge port (for plug-in software), the RF channel switch, the RF video out (for connection to a TV set), the A/V port (for connection to a monitor), the serial port (usually used for disk drives), the cassette connector (for audiocassette data storage), and the "user port" for RS-232 serial applications and special accessories. That's an impressive array of ins and outs for such a low-cost PC.

After opening the case, you need only detach the internal keyboard connector and the power indicator LED from the motherboard to split the unit into two halves. The upper half contains a keyboard assembly screwed in place (plenty of screws there), while the lower half contains the motherboard. At this point, shiny RF shielding (which prevents radio interference with nearby TV or radio devices) obscures the innermost parts of the computer. But not for long...

Having set the upper half (keyboard assembly) aside for a moment, we've separated the lower half of the C64 into three parts: the plastic housing, the top RF shield, and the motherboard. Only a few screws held the motherboard to the case, and three of those held the top RF shield in place. The clear plastic piece (at the top of the photo) is the power LED connected to its red and black wires.

This is where it all happens. The original C64's motherboard held a total of 40 chips (some of them hidden from view here), which did all the main processing. By 1992, the number of chips on the motherboard had been reduced by a third, to cut costs. The metal box visible at the upper edge of the motherboard (the one with the small yellow sticker on it) contains the unit's video circuitry, including the RF modulator, which prepares audio and video for a TV set's antenna terminal.

The largest silver box on the motherboard--the one with the multiple ventilation holes, houses a large purple chip called the VIC-II (for "Video Interface Chip"). This chip handles all of the C64's graphics duties. The silver enclosure provides RF shielding and acts as a heat sink for the inordinately hot-running VIC-II.

The VIC-II chip, which was originally ceramic, was changed to plastic in later runs of the C64. Unfortunately, the plastic chips didn't conduct heat as well as the ceramic chips, and the VIC-II became a common point of failure in many C64 machines. It's one of several instances where cost-cutting measures hurt the good design and longevity of the Commodore 64.

Now let's zoom in on a few of the motherboard's other important chips. The C64's CPU, the MOS 6510 (the longest black chip in this photo) is a marginally improved 6502 CPU, but it runs at a painfully slow 1 MHz.

The best-known of the Commodore 64's chips these days is probably the 6581 SID synthesizer chip (center of photo), which creates the tinny, raspy sounds that people can't get enough of. In the 80s, the SID (short for "Sound Interface Device") was the most advanced sound-generating chip of its kind, and musicians everywhere still prize the SID's low-fi retro sounds.

Here we see the C64 keyboard assembly detached from the upper half of the case. In a previous PC World article, I listed the C64 keyboard as the 10th worst PC keyboard of all time, which generated considerable venom from some die-hard C64 fans. Nevertheless, I stand by my opinion because of the C64 keyboard's anti-ergonomic design and confusingly odd key layout. But I'll concede that, for an inexpensive computer, the C64 keyboard got the job done--especially since expectations at the time were undoubtedly far lower than they are today. Compared with contemporaneous consumer boards, some of which had keys the size of Chiclets, the C64's keyboard probably seemed vastly superior.

Now let's take a look inside the keyboard. Beneath each key cap is a plastic plunger (the black pieces above), each of which has a small conductive rubber pad at its base. When the user pushes down on the key, the pad completes a circuit between a pair of copper contacts on the underlying circuit board (shown on the right). When the key is released, a spring pushes the key back up.

The Commodore 64's roomy case led many users to refer to the computer as "the breadbox"--certainly a more affectionate (though no less evocative) name than "the doorstop."

Now reassembled, the C64 sits wrapped in its handsome imitation leather dust cover. Though this particular machine doesn't do much computing these days, it serves as a valuable reminder of the PC's past.

Among aficionados, the question of what the C64's true impact was on the many PCs that came after it still sparks considerable disagreement. Early critics often derided it as a toy computer, and there's some truth to that appraisal: The Commodore 64 easily played game console to the IBM PC. But if the C64 was a toy computer, it was a toy computer that sold 17 million units. And though it failed to garner a spot in our list of "The 25 Greatest PCs of All Time" a couple of years ago, many nostalgic fans insist that the Commodore 64 was not merely a hugely popular machine, but a great one.

Whether the C64 did or did not have a lasting influence on the innovation and design of computers, it surely had a lasting effect on people. Millions of families' first PC was a Commodore 64, helping to ignite a firestorm of interest in personal computing that continues to transform our culture today.