At the Microsoft event for the Surface, the representatives often referred to the device as a PC rather than as a tablet. This is a fundamentally different approach than what Apple took with the iPad. Steve Jobs called the iPad a "post-PC device that needs to be easier to use than a PC" [source: Rosoff]. But when you look at how the Surface works, you can see the distinctions between PC and tablet aren't always clear.
Like a PC, the Surface has a central processing unit (CPU). It's the CPU's job to execute operations on data. This is how computers run programs -- the programs require the CPU to take information and perform some sort of operation on it and then present the result.
The Surface also has memory like a PC. Memory is where a computer stores data until it's needed for an operation. A computer's speed depends partly on the power of the processor and partly on how much memory the computer has at its disposal. With more memory, the computer can hold more data in temporary storage. This removes the need for the CPU to pull data from a hard drive, which can be a slower process. The Surface has solid state memory, which is like a PC's hard drive. This is where the Surface stores applications and files.
Another similarity between the Surface and a PC is the motherboard. The motherboard is a special type of circuit board. It allows the various electronic components within the Surface to connect to each other through dedicated pathways. This is what lets the CPU pull information from memory or hard drive space. It also creates the path for the graphics processor to send information to the display. It's sort of like the nervous system for the device.
The Surface's touch-screen interface sets it apart from an average computer. It uses a capacitive screen, meaning that the computer detects when there is a change in the electrical potential across the screen. When you touch the screen, your finger interrupts a weak electric field. Circuits at the edges of the screen detect the decrease in electrical charge across the screen. The circuits identify the location of your finger and register it as a touch, mapping it to a command.
Most tablets share these qualities. Does that mean all tablets are PCs? They're definitely all computer devices. Whether or not they qualify as a full PC depends more upon your personal definition of what makes a personal computer.