C H A P T E R 2

Container Views

Each tap on a scroll arrow moves one unit in the chosen direction. Your application determines how much one unit is. For example, the Notepad moves one note for each tap on the arrow; for a note longer than the view, each tap scrolls the number of displayed lines minus one. The Names File application moves one “card” for each tap. The Date Book’s day-at-a-time view moves one day for each tap, and the week-at-glance view moves a week per tap. Time Zones moves from city to city alphabetically. If your application’s information falls naturally into sections, each tap on a scroll arrow should scroll one section. If not, scroll a screenful minus one line at a time (a “page”).

Whether your application should scroll smoothly or unevenly depends on the type of information being scrolled. With smooth scrolling, each tap on a scroll arrow moves the same amount. That is how the Date Book, Names File, Calculator, and Time Zones applications work, for example. In some cases, uneven scrolling is better than smooth scrolling. The Notepad scrolls by uneven increments—note by note—to take advantage of a user’s visual memory of where he or she wrote things.

While scrolling up by uneven increments, an application may encounter an item that is too large to display all at once. Since the application can’t show the whole item, it must either show the bottom of the item or the top of the item. The appropriate response depends on whether the view scrolls page-by- page or continuously like a roll of paper. A view that scrolls continuously should scroll up to the bottom of an item that is too large to show all at once. A view that scrolls page-by page should scroll up to the top of an item that is too large to show all at once. For instance, the Notepad (which scrolls like a roll of paper) scrolls up to the bottom of a note that is taller than the height of the Notepad main view. In contrast, the Out Box (which scrolls detail items page-by-page) would scroll up to the top of the same note.

Universal Scroll Arrows

Newton devices have two universal scroll arrows for user control of scrolling. The universal scroll arrows are part of the Newton system; they are not attached to one view. On an Apple MessagePad 120, they are located in the center of the screen, below the display area. Figure 2-31 shows the universal scroll arrows.

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How Views Work

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Apple 2 manual Universal Scroll Arrows

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.