Text mode demos - AbsoluteAstronomy.com

Text mode demos are real-time calculated computer animation

Computer animation

Computer animation is the process used for generating animated images by using computer graphics. The more general term computer generated imagery encompasses both static scenes and dynamic images, while computer animation only refers to moving images....

s which make use of the native text graphic mode(s) common on the IBM PC compatible

IBM PC compatible

IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...

s. The text mode demo scene is one of many different facets of the demoscene

Demoscene

The demoscene is a computer art subculture that specializes in producing demos, which are non-interactive audio-visual presentations that run in real-time on a computer...

.

Text mode

Text mode

Text mode is a kind of computer display mode in which the content of the screen is internally represented in terms of characters rather than individual pixels. Typically, the screen consists of a uniform rectangular grid of character cells, each of which contains one of the characters of a...

as a medium offers several unique challenges for the creators of such a demo. Similar to the constraints of ASCII

ASCII art

ASCII art is a graphic design technique that uses computers for presentation and consists of pictures pieced together from the 95 printable characters defined by the ASCII Standard from 1963 and ASCII compliant character sets with proprietary extended characters...

and ANSI art

ANSI art

ANSI art is a computer art form that was widely used at one time on BBSes. It is similar to ASCII art, but constructed from a larger set of 256 letters, numbers, and symbols — all codes found in IBM code page 437, often referred to as extended ASCII and used in MS-DOS and Unix environments...

, the coder and artist both must take into consideration the limitations presented by text mode: a base resolution of 80×25 "blocks" and a mere 16 fixed colors by default.

Pseudographic resolution

By taking advantage of half blocks characters 220 (DCh) (bottom half) or 223 (DFh) (upper half) in the code page 437

Code page 437

IBM PC or MS-DOS code page 437 is the character set of the original IBM PC. It is also known as CP 437, OEM 437, PC-8, MS-DOS Latin US or sometimes misleadingly referred to as the OEM font, High ASCII or Extended ASCII....

(adapter's native) character set, one can effectively double the vertical resolution (from 80×25 to 80×50 in the default text mode).

Enhanced Graphics Adapter

Enhanced Graphics Adapter

The Enhanced Graphics Adapter is the IBM PC computer display standard specification which is between CGA and VGA in terms of color and space resolution. Introduced in October 1984 by IBM shortly after its new PC/AT, EGA produces a display of 16 simultaneous colors from a palette of 64 at a...

(EGA

Enhanced Graphics Adapter

) and better adapters natively support text modes beyond 80×25 character cells: 80×43 (EGA), 80×50 (Video Graphics Array

Video Graphics Array

Video Graphics Array refers specifically to the display hardware first introduced with the IBM PS/2 line of computers in 1987, but through its widespread adoption has also come to mean either an analog computer display standard, the 15-pin D-subminiature VGA connector or the 640×480 resolution...

, VGA

Video Graphics Array

), 132×50 and 132×60 (VESA

VESA BIOS Extensions

VESA BIOS Extensions is a VESA standard, currently at version 3, that defines the interface that can be used by software to access compliant video boards at high resolutions and bit depths...

compatible Super VGA), etc., increasing the simulated graphic resolution available, doubled again through the half block characters.

Also, by tweaking

Tweaking

Tweaking refers to fine-tuning or adjusting a complex system, usually an electronic device. Tweaks are any small modifications intended to improve a system....

the display's hardware, higher resolutions can be achieved. For example, a tweak mode can be set even in the original IBM Color Graphics Adapter

Color Graphics Adapter

The Color Graphics Adapter , originally also called the Color/Graphics Adapter or IBM Color/Graphics Monitor Adapter, introduced in 1981, was IBM's first color graphics card, and the first color computer display standard for the IBM PC....

(CGA

Color Graphics Adapter

) to give an extra, non-standard 160×100 pixels, 16-color graphic mode.

Custom graphics and effects can also be achieved by customizing the character set (with the EGA and better adapters) on a per-pixel

Pixel

In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....

basis. Halving the available colors from 16 to 8, up to two customized character sets can be used simultaneously on screen with most Super VGA graphic cards, blurring the border between pure text mode

Text mode

s and true graphic modes.

Expanding colors

In text mode, the blinking attribute effect is enabled by default, giving sixteen colors available for the foreground but only eight for the character cell background. By disabling the blinking effect, all 16 colors available can be used for both the background and the foreground of every character cell.

Creatively making use of the three shaded block characters 176 (B0h) (25% halftone), 177 (B1h) (50% halftone) and 178 (B2h) (75% halftone) in the CP437

Code page 437

character set, one can achieve some interesting color combinations with the limited palette

Palette (computing)

In computer graphics, a palette is either a given, finite set of colors for the management of digital images , or a small on-screen graphical element for choosing from a limited set of choices, not necessarily colors .Depending on the context In computer graphics, a palette is either a given,...

.

With the EGA and the VGA the color palette can be expanded from the original fixed 16-color CGA palette to 16 out of 64 colors (EGA palette) or 16 out of 262,144 colors (VGA palette), allowing smoother color transitions.

Text mode demoscene

The first evident IBM PC

IBM PC compatible

demo group to create text mode demos is said to be the Sorcerers. The ever-popular Finnish

Finland

Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

group Future Crew

Future Crew

Future Crew is a now-defunct Finnish demogroup who created PC demos and software, active mostly between 1992 and 1994.-History:The group was founded in 1986 by PSI as a Commodore 64 group, before moving to the PC demoscene in 1988; other members included, over time, Trug, Wildfire, Pixel, ICE,...

also began by creating some innovative creations which took advantage of text mode, with text intros such as "Yo!" and "Starport".

tAAt

TAAt

tAAt is a Finnish humor-based demogroup founded in 1992 which is active in participating and organizing demoscene events...

, a non-profit organization in Finland

Finland

, has been organizing a semi-annual competitive event for authors of textmode demos called the Text Mode Demo Contest

Text Mode Demo Contest

Text Mode Demo Contest is a semi-annual text mode demo competition organized by tAAt ry and held over the internet. The inherent limitations of text mode graphics create unique challenges for demosceners. To help promote the event, a text mode invitation demo is released ahead of the competition....

(TMDC) from 1996 to 2007 inclusively. After they announced they wouldn't continue the annual competition after TMDC 10, members of the Northern Dragons demogroup decided to take the organization of TMDC in charge.

External links

Text Mode Demo Archive
Text Mode Demo Compo (TMDC)
FAQ Page about Demos
libcaca, the Colour AsCii Art library
Interview with Jari Komppa organizer of the TMDC, September 2007

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