C H A P T E R 6

Data Input

A scrolling list is not the best way to input one value across a range of values. Since the full range isn’t visible all at once in a scrolling list, users have a hard time understanding the scope of their choices. Pickers work well for listing discontinuous values across a range, such as 1 minute, 5 minutes,

10 minutes, 30 minutes, and Never. Sliders work very well for displaying a continuous range of values and for letting users choose any value in the range.

Radio Buttons

For a field that can have just one of a few unchanging values, an application can use a cluster of radio buttons. A user selects an input from a cluster of radio buttons by tapping one of the radio buttons. This automatically deselects the previously selected radio button in the cluster. A cluster of radio buttons always offers the same choices; the radio buttons never change dynamically depending on context. Figure 6-4 shows a sample cluster of radio buttons.

Figure 6-4With radio buttons, a user can select one value for a field

The selected radio button is black

Notice that a cluster of radio buttons offers a user the same choices as a short picker. On the downside, radio buttons take up more space in a view than

a picker because they are always visible in the view. On the upside, being always visible makes radio buttons faster and easier to use than a picker. There’s no need to tap and a wait (however briefly) for anything to pop up.

For a detailed description of radio buttons, see “Radio buttons” on page 3-1.

6-6Tapping

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Apple 2 manual Radio Buttons, 4With radio buttons, a user can select one value for a field
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2 specifications

The Apple II is a defining product in the history of personal computing, first introduced in 1977 by Apple Computer, Inc. Designed by Steve Wozniak, the Apple II was one of the first highly successful mass-produced microcomputer products and played a significant role in bringing personal computers into homes and schools.

One of the Apple II's standout features was its color graphics capability. It was one of the first personal computers to provide color output, thanks to its built-in video interface. The initial model supported a resolution of 280x192 pixels with a palette of 6 colors, which allowed for vibrant visuals that set it apart from contemporaries like the monochrome Altair 8800.

The Apple II was notable for its open architecture. This design allowed users to expand the computer's capabilities easily through a series of expansion slots. Users could add floppy disk drives, additional memory, and various peripheral devices, making the system highly adaptable to individual needs. This encouraged a thriving ecosystem of third-party hardware and software, which contributed to its popularity.

Another significant feature was its use of the 6502 microprocessor. This 8-bit CPU was not only affordable but also powerful for its time, allowing the Apple II to run various applications efficiently. Along with a built-in keyboard and an innovative plastic case that housed its components, the design was user-friendly and appealing.

The Apple II also introduced the concept of “bootable software” through the use of floppy disks. The disk operating system (DOS) allowed users to store and run multiple programs without having to reload software manually, providing a level of convenience that had not been widely available before. Key software like VisiCalc, the first spreadsheet program, helped boost sales, showcasing the Apple II's utility in business and education environments.

The computer was also well-known for its early adoption of BASIC programming language. Apple provided an operating system that supported Applesoft BASIC, which enabled users, including students, to write their programs, further fostering a community of developers.

In summary, the Apple II's color graphics, open architecture, powerful 6502 processor, innovative use of floppy disks, and support for BASIC programming made it a revolutionary product in its time. Its legacy laid the groundwork for future personal computers and established Apple as a leader in the burgeoning tech industry. The Apple II remains an iconic symbol of the early personal computing era, reflecting a generation's transition into a digitally connected world.
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