Numerous add-on video display cards were available for the Apple II series, such as the Apple 80-Column Text Card. In the II GS it was an output for an analog RGB monitor specially designed for the II GS. In the IIc and IIc Plus, this connector was a special-purpose video connector for adapters to digital RGB monitors and RF modulators. In addition to the composite video output jack, the IIc, IIc Plus, and the II GS featured a two-row, 15-pin output. (The exception was the Extended Back version of the Bell & Howell branded black II Plus, which did provide proper video sync, as well as other media oriented features.) However the quality of this output was unreliable the sync signaling was close enough for monitors-which are fairly forgiving-but did not conform closely enough to standards to be suitable for broadcast applications, or even input to a video recorder, without intervening processing. This enabled the computer to be connected to any composite video monitor conforming to the same standard for which the machine was configured. Then, to go back to mixed graphics and text, one would access 0xC053 (49235).Īll Apple II machines featured an RCA jack providing a rough NTSC, PAL, or SECAM composite video output (on non-NTSC machines before the Apple IIe this output is black-and-white only). For example, one could switch from mixed graphics and text to an all-graphics display by accessing location 0xC052 (49234). This allowed the user to do many different things including displaying the graphics screen (any type) without erasing it, displaying the text screen, clearing the last key pressed, or accessing different memory banks. The value read or written does not matter, what counts is the access itself. Reading a value from, or writing any value to, certain memory addresses controlled so called " soft switches". While these occur in all graphics modes, they play a crucial role in Hi-Resolution or Hi-Res mode (see below). Apple's text and graphics modes are based on two different interleave factors of 8:1 and 64:1.Ī second peculiarity of Apple II graphics-the so-called "color fringes"-is yet another by-product of Wozniak's design. Many home computer systems of the time (as well as today's IBM PC compatibles) had an architecture which assigned consecutive blocks of memory to non-consecutive rows on the screen in graphic modes, i.e., interleaving. One notable peculiarity of these modes is a direct result of Apple founder Steve Wozniak's chip-saving design. The graphic modes of the Apple II series were peculiar even by the standards of the late 1970s and early 1980s. The 1986 Apple IIgs split from previous Apple II architecture and the graphics have more in common with the Atari ST and Amiga. Internally, Apple II graphics modes are idiosyncratic and do not simply use a linear frame buffer. The Apple IIe added "double" versions of each of these, most prominently "double high resolution" with twice the horizontal resolution in 16 colors. They consist of a 16 color low resolution mode and a high resolution mode where visuals are dependent on artifact color. ( Learn how and when to remove this template message)Īpple II graphics debuted on the 1977 Apple II and was used throughout the Apple II line.
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