Published in autumn 2026, the primer uses screen as the Amiga operating system’s term for a graphics area. Programs could open multiple screens with separate resolutions and colour depths. Hardware documentation also uses playfield for such an area, while demo programmers may discuss raster splits.

The article focuses on the original graphics hardware, OCS. Later ECS and AGA systems removed some restrictions, while retaining the same basic screen model. Amiga screens use indexed palettes. Each screen has a limited set of colour registers, whose values come from a 12-bit colour space on OCS and ECS, or a 24-bit space on AGA.

Planar graphics stores each bitplane separately. A one-bitplane screen provides two colour indices, two bitplanes provide four, and so on. OCS supports up to five bitplanes and 32 colours. AGA can use eight bitplanes and 256 colours.

On OCS and ECS, the available bitplane count depends on the display resolution. In PAL low-resolution mode, an OCS Amiga produces 320x256 pixels, or 320x512 with interlace, with up to 32 colours. High-resolution mode produces 640x256 pixels, or 640x512 interlaced, with up to 16 colours. Overscan can extend high resolution to 724x283, although the full area is not guaranteed to be visible on every monitor or television.

Low-resolution screens can use a sixth bitplane for HAM, which can show all 4096 OCS colours simultaneously with limitations. The same bitplane can support EHB, which adds 32 half-bright copies to a 32-colour palette. Planar graphics also suited the Amiga’s preemptive multitasking. A text editor could use a two-colour screen while a graphics program used a 32-colour screen, and each screen required only the bits needed for its pixels. Screens could also have arbitrary sizes and positions, reducing memory use further.

The graphics hardware could reposition or scroll a screen quickly. Workbench could use a desktop larger than the visible display and let the user move around it. The copper, a video-synchronised co-processor, could change resolution, colour depth and palette values during the redraw cycle. Multiple screens could therefore appear together and overlap. AMOS supplied its own screen abstractions for these operations.

The copper also controls colour registers and hardware sprites. Changing a register on each horizontal line creates copper gradients or copper bars, producing effects and additional visible colours beyond the 32 palette indices. A game could combine 32 colours in its main area with 32 different colours in a user interface or status area.

Users could switch between complete screens with a button at the top right or a system-wide keyboard shortcut. They could also drag a screen’s title bar downward to expose another running program behind it. The article considers this useful in limited cases, such as checking a download while a chat program remains available, and notes that ordinary screen switching is usually easier.

A demonstration runs on an Amiga 600 with a 7 MHz processor, or 0.007 GHz, using hardware broadly equivalent to the original Amiga 1000 from 1985. The machine plays music while running a text editor and Deluxe Paint, and performs screen switching and dragging. The demonstration was filmed from a flat-screen monitor.

Dual Playfields let two overlapping screens share the display. Colour index 0 on the foreground screen becomes transparent, revealing the screen underneath, while its other indices remain visible. Each playfield can still be scrolled, painted and given its own palette. One example uses a four-colour background with burgundy scenery and pink stars, green and purple sprites placed between the layers, and an eight-colour foreground. The hardware keeps the layers moving smoothly on a 7 MHz machine. The associated intro can be downloaded or watched through Demozoo.

The article compares this model with modern windowed desktops. It mentions maximized Visual Studio Code, 80-column terminals, 5:4 displays for orthodox file managers and virtual desktops. In Directory Opus, pushing the pointer to a screen edge and clicking can open the parent directory in the corresponding lister. A window-based system can reproduce the command, although a screen edge gives the pointer a useful physical boundary. The text also praises the proportions of an 80x24 character display for code and terminal applications.

The primer leaves several topics for further reading. Planar graphics supports effects that manipulate only selected bitplanes. The blitter can copy graphics memory quickly and combine or mask bitplanes. Sprites can add colours to low-bitplane screens and can be multiplexed. For more detail, the article recommends Codetapper’s Amiga Site, especially its analysis of Shadow of the Beast, whose graphics use several layers of smooth parallax scrolling.

Its conclusion is practical: Amiga screens combine memory-saving planar graphics with independent dimensions, palettes and colour depths. They can overlap, scroll, switch instantly and slide apart to reveal other screens. Dual Playfields add transparency between layers. The operating system and applications used these capabilities to support multitasking on limited hardware and at low display resolutions.