The Commodore 64 (C64) demos are demonstrations of what can be done to push the limits of the Commodore 64 computer, made by programmers, musicians and artists.
Though it was not unusual to find demos that displayed a single picture, only music tracks or a programming skill, groups were formed that consisted of members who were skilled in composing music, drawing graphics and programming. Full disk demos were produced, some of which would play music as the next file loaded, without any delay in the sound.
Borders - screen shot of the intro to the "Bobby Border" part of the "Camel Park" demo. Notice the borders in black.All borders removed - screen shot of one of the main effects in the "Bobby Border" part of "Camel Park". Notice how the sprites move into the borders. Also an example of the DXYCP (sprite-scroller) effect.
Various effects are achieved in demos, most of them due to undocumented side-effects pertaining to the MOS Technology VIC-II chip. Some examples are:
Sprite scrollers were placed in the border. By tricking the hardware not to draw the border around the screen, sprites could be moved into this area and displayed.
Sprites were multiplexed across vertical raster lines (over 8 sprites, sometimes up to 120 sprites). A common perception is that no more than 8 sprites could appear at once on the screen, but assigning new Y coordinates once it has started being drawn made it reappear further down the screen.
FLD (flexible line distance) moved bitmap or character rows an arbitrary number of vertical raster lines apart, making it possible to arbitrarily move any 8 pixel high graphic block smoothly up and down across the screen. Adding sine curves to this positioning provided a wavy effect.
FLI, or Flexible Line Interpretation, can be used to increase the number of unique colors which can appear in an 8×8 or 8×4 block on the screen. This mode is occasionally extended further with sprites and/or interlacing two bitmaps together (as in SHIFLI or UIFLI). These modes usually cause the left-most 24 pixels of the display to become unusable.
FPP (Flexible Pixel Positioning), basically a variation of the FLI mode, allows the placement of any line of a character-based graphic at any one y-position, allowing for effects like x-rotating logos, barrel-like effects or smooth stretching and waving over the whole screen.
Tec-Tec (also Tech-Tech or Tic Tac) assigns a new x-position to any line of a graphic. By using animated sine waves you could for example wave a logo horizontally over the screen.
VSP (Variable Screen Positioning), also known as HSP, allows arbitrary x-placement of a bitmap, with the bitmap wrapping around at the border.
A Linecruncher allows the user to scroll a bitmap larger than one screen vertically without having to move all the bitmap data manually.
AGSP (Any Given Screen Position) is the combination of VSP and Linecruncher, for example making possible games with colorful bitmap graphics that scrolled, such as Hannes Sommer's "Fred's Back" series.
Followers of the C64 would see the growth of the demo scene. Gone were the single file demos with one scrolling text and no music. Full disk demos were produced, some of which would play music as the next file loaded, without any delay in the sound.
Hidden parts were included as was the occasional game implemented into a demo.
When the Commodore Amiga appeared, many former C64 demo programmers switched platforms and continued to make demos for the Amiga (see Amiga demos). The Atari demos were also heavily influenced by C64 demos. In the United Kingdom, the main alternative demo scene was the one of ZX Spectrum demos.
The C64 was popular in a time when local BBSes were also popular and used to communicate with other people. Software trading via mail was also common. Some C64 enthusiasts lament the loss of the social interaction that locally centered computer activities provided.
Commodore Scene Database, A scene database where you can get in touch with the sceners themselves or get info about one scener or release or event. Structured, including information (hidden parts), downloads, screenshots, forum.
C64 PortalC64 demo scene related news, about new releases, parties and other scene related news
Intros.C64.OrgLarge online archive of crack intros, the first demoscene productions.
Driven OnlineDriven Online - Covering the North American demo scene
The Commodore 64, also known as the C64, is an 8-bit home computer introduced in January 1982 by Commodore International. It has been listed in the Guinness World Records as the highest-selling single computer model of all time, with independent estimates placing the number sold between 12.5 and 17 million units. Volume production started in early 1982, marketing in August for US$595. Preceded by the VIC-20 and Commodore PET, the C64 took its name from its 64 kilobytes(65,536 bytes) of RAM. With support for multicolor sprites and a custom chip for waveform generation, the C64 could create superior visuals and audio compared to systems without such custom hardware.
The Original Chip Set (OCS) is a chipset used in the earliest Commodore Amiga computers and defined the Amiga's graphics and sound capabilities. It was succeeded by the slightly improved Enhanced Chip Set (ECS) and the greatly improved Advanced Graphics Architecture (AGA).
Parallax scrolling is a technique in computer graphics where background images move past the camera more slowly than foreground images, creating an illusion of depth in a 2D scene of distance. The technique grew out of the multiplane camera technique used in traditional animation since the 1930s.
A crack intro, also known as a cracktro, loader, or just intro, is a small introduction sequence added to cracked software. It aims to inform the user which "cracking crew" or individual cracker removed the software's copy protection and distributed the crack.
Bit blit is a data operation commonly used in computer graphics in which several bitmaps are combined into one using a boolean function.
The demoscene is an international computer art subculture focused on producing demos: self-contained, sometimes extremely small, computer programs that produce audiovisual presentations. The purpose of a demo is to show off programming, visual art, and musical skills. Demos and other demoscene productions are shared, voted on and released online at festivals known as demoparties.
The Commodore Plus/4 is a home computer released by Commodore International in 1984. The "Plus/4" name refers to the four-application ROM-resident office suite ; it was billed as "the productivity computer with software built in".
The VIC-II, specifically known as the MOS Technology 6567/6566/8562/8564, 6569/8565/8566 (PAL), is the microchip tasked with generating Y/C video signals and DRAM refresh signals in the Commodore 64 and Commodore 128 home computers.
Pixel art is a form of digital art drawn with graphical software where images are built using pixels as the only building block. It is widely associated with the low-resolution graphics from 8-bit and 16-bit era computers, arcade machines and video game consoles, in addition to other limited systems such as LED displays and graphing calculators, which have a limited number of pixels and colors available. The art form is still employed to this day by pixel artists and game studios, even though the technological limitations have since been surpassed.
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The raster bar is an effect used in demos and older video games that displays animated bars of colour, usually horizontal, which additionally might extend into the border, a.k.a. the otherwise unalterable area of the display. Raster bar-style effects were common on the Atari 2600 and Atari 8-bit computers and then later in demos for the Commodore 64, Amiga, Atari ST, and Amstrad CPC.
A display list, also called a command list in Direct3D 12 and a command buffer in Vulkan, is a series of graphics commands so that they may be later run when the list is executed. Systems that make use of display list functionality are called retained mode systems, while systems that do not are as opposed to immediate mode systems. In OpenGL, display lists are useful to redraw the same geometry or apply a set of state changes multiple times. This benefit is also used with Direct3D 12's bundle command lists. In Direct3D 12 and Vulkan, display lists are regularly used for per-frame recording and execution.
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A raster interrupt is an interrupt signal in a legacy computer system which is used for display timing. It is usually, though not always, generated by a system's graphics chip as the scan lines of a frame are being readied to send to the monitor for display. The most basic implementation of a raster interrupt is the vertical blank interrupt.
The demo effect is a name for computer-based real-time visual effects found in demos created by the demoscene.
The Judges was a Dutch Commodore 64 group from Roosendaal known for being one of the earliest dedicated demogroups. The Judges released several demos for the Commodore 64 home computer between the years 1986 - 1988. Groups such as The Judges are regarded as early pioneers of what came to be known as the demoscene.
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GrafX2 is a bitmap graphics editor inspired by the Amiga programs Deluxe Paint and Brilliance. It is free software and distributed under the GPL-2.0-only license.
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