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PROGRAMMED BRAINS 431

If your SBC doesn’t come with an operating system, you need to provide one. DOS is a good
all- around choice for robots that don’t need the bells and whistles of Windows. Microsoft no
longer sells its once venerable MS- DOS, which at one time was packaged with almost all PCs.
G There are many free open- source alternatives, such as FreeDOS and DR- DOS, available for
download from the Web.
You can also sometimes find surplus 3- 1/2″ diskettes of MS- DOS 5 and 6 in the dusty- shelf
section of old surplus stores. You need a 3- 1/2″ disk drive to read the content of the disks and
transfer it to the solid- state memory used by most SBCs.

SBC Form Factors
Single- board computers come in a variety of shapes and forms. A standard form factor sup-
ported by many manufacturers is PC/104, which measures about 4″ square. PC/104 gets its
name from “Personal Computer” and the number of pins (104) used to connect two or more
PC/104- compatible boards together.

SBC Kits
To handle different kinds of jobs, SBCs are available in larger or smaller sizes than the 4″ by
4″ PC/104. And while most SBCs are available in ready- made form, they are also popular as
kits. For example, the HandyBoard, designed by instructors at MIT, is a single- board computer
based on the Motorola 68HC11 microcontroller. It is available already assembled or as a kit.

PERSONAL COMPUTERS
Having your personal computer control your robot is an admirable use of available resources,
but it’s not always practical if you’re planning on mounting the thing on top of good old Tobor
(that’s robot spelled backward). The old- style desktop PC is simply too heavy, bulky, and
power hungry to be an effective source of brains for your bot.
There are two ways to use a PC to control your robot:

• Brains on bot. Mount the computer on the robot. For a laptop, you can rely on its internal
battery. But for a desktop PC meant to be plugged into the wall, you’ll need to either run
the computer using a large 12- volt battery and car power inverter or retrofit the computer
with a power supply that can be juiced directly from the battery.
• Brains off bot. You use any kind of computer and link it to your robot via wires, radio
frequency (RF) link, or optical link. This is common practice when using tabletop robotic
arms; since the arm doesn’t scoot around the floor, you can place it beside your PC and
tether the two via wire. A USB connection is a favorite tethering technology— not to men-
tion inexpensive and easy to use. There’s also Bluetooth, Zigbee, and other types of radio
links if you don’t want the wires.

Using an On- Bot PC
You have quite a few options for mounting a PC on your robot.

Laptops and Netbooks
The ideal computer for onboard brains is a laptop running your favorite operating OS. Lap-
tops carry their own rechargeable batteries and are made to be lightweight. You can use your
regular laptop or else purchase one specially for your bot. You don’t need a new laptop; find
one used and save a few bucks.

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