Peter Hahn, resident at Cornell Medical Center proudly displaying the Palm Pilot he uses as a drug database.

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­Personal Digital Assistants (PDAs) are tightly integrated computers that often use flash memory instead of a hard drive for storage. These computers usually do not have keyboards but rely on touchscreen technology for user input. PDAs are typically smaller than a paperback novel, very lightweight with a reasonable battery life. A slightly larger and heavier version of the PDA is the handheld computer.