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Hold-And-Modify

Hold-And-Modify (HAM) is a specialized display mode developed for the Commodore Amiga computer, enabling the simultaneous presentation of up to 4,096 colors on screen through a unique pixel color encoding technique that leverages six bit planes to achieve 12-bit color depth (4 bits each for red, green, and blue).^[1] This mode operates by either selecting one of 16 palette colors using the lower four bit planes or, for modification, retaining the color of the adjacent previous pixel and altering a single color component (red, green, or blue) based on the values in bit planes 5 and 6, which dictate the modification type: '00' for standard selection, '01' for blue adjustment, '10' for red, and '11' for green.^[1] Introduced with the original Amiga chipset in 1985, HAM was designed to expand the effective color gamut beyond the standard 16-color limitation of earlier modes, making it particularly suited for rendering smooth gradients, detailed images, and photographic content on hardware with constrained memory.^[1] To activate HAM, the system sets bit 11 (HOMOD) in the BPLCON0 register, requires single-playfield operation (DBLPF bit cleared), and configures six bit planes (BPU bits set to 110).^[1] It supports low-resolution formats such as 320×200 (NTSC non-interlaced) or 320×256 (PAL non-interlaced), and can extend to high-resolution 640×200 or 640×256 when the HIRES bit is enabled, though the modification mechanism inherently propagates horizontally from left to right across scanlines.^[1] Programmers often simplify implementation by basing the entire screen on modifications of a single background color from register COLOR00, minimizing the need for full palette management across all 32 system color registers.^[1] While innovative for its era, HAM's dependency on sequential pixel processing introduced artifacts like color bleeding if not carefully managed, influencing its use in applications such as image viewers (e.g., Digi-View) and early multimedia software.^[2] The mode's legacy persists in Amiga emulation, demoscene productions, and retro computing recreations, highlighting the Amiga's pioneering role in affordable high-color graphics.^[3]

History and Background

Development on the Amiga

The Hold-And-Modify (HAM) mode originated from the efforts of Jay Miner and the engineering team at Amiga Corporation, founded in 1982, and Commodore-Amiga following the acquisition in August 1984. It became a core feature of the Original Chip Set (OCS) designed to overcome the limitations of the Amiga's standard 16-color palette by enabling expanded color reproduction in graphics-intensive applications.^[4] This innovation stemmed from Miner's exposure to advanced military flight simulators at Singer-Link, where he observed photorealistic visuals and sought to replicate similar capabilities in a cost-effective home computer system.^[5] HAM was specifically integrated into the Denise video chip within the OCS, which handled real-time color lookup and pixel processing to support dynamic modifications without requiring external hardware additions.^[6] The mode leveraged the Amiga's planar memory architecture, where bitplanes stored individual color bits across the screen, allowing efficient data fetching by Agnus (the memory controller) and conversion by Denise into display signals.^[6] Design constraints played a pivotal role, including a 12-bit color depth limited to 4 bits per RGB channel to balance visual fidelity with the era's chip fabrication capabilities and memory bandwidth.^[6] Overall, HAM enabled up to 4096 simultaneous colors, marking a significant advancement in affordable multimedia hardware.^[6]

Introduction and Initial Impact

The Hold-And-Modify (HAM) mode debuted with the Commodore Amiga 1000 on July 23, 1985, introducing a groundbreaking graphics capability that allowed for the simultaneous display of up to 4096 colors in a resolution of 320x200 pixels.^[7]^[8] This was a significant advancement over contemporary systems, such as the Atari ST, which supported a maximum palette of 512 colors with only 16 displayed on screen at low resolution.^[9] By leveraging a specialized encoding technique that held a previous pixel's color and modified components for adjacent ones, HAM enabled richer visual fidelity on the Amiga's original chipset (OCS).^[8] Immediately following its launch, HAM found applications in early Amiga demos, games, and productivity software, where it facilitated photorealistic imagery that captivated users and developers. Similarly, productivity tools like Deluxe Paint incorporated HAM support for bitmap editing, allowing artists to work with thousands of colors in still images and animations.^[10] These uses highlighted HAM's potential for static visuals, such as digitized photographs and artwork, in an era when most systems were limited to dozens of colors. The introduction of HAM received widespread praise in the computing industry for its innovative approach to color display, which elevated the Amiga's reputation as a multimedia powerhouse and influenced subsequent color expansion techniques in competing platforms during the late 1980s.^[11] However, it was also criticized for its programming complexity and performance limitations, particularly the mode's slowness for real-time animation due to the need for sequential pixel dependencies.^[11] Key milestones included its integration into the AmigaOS Intuition graphics library, which provided developers with API access to HAM screen modes from launch, and detailed documentation in the 1986 Amiga Hardware Reference Manual, which outlined the mode's hardware implementation for broader adoption.^[10]^[12]

Principles of Operation

Color Encoding Mechanism

The Hold-And-Modify (HAM) color encoding mechanism operates by using six bitplanes to generate pixel colors in a 12-bit RGB color space, allowing up to 4096 distinct colors through sequential modifications rather than direct palette indexing.^[6] In this mode, each pixel's color is derived from either a direct selection from a 16-color palette or a modification of the immediately preceding pixel's color, with changes limited to one RGB channel per pixel to conserve bitplane bandwidth.^[13] The process relies on two control bits (from bitplanes 5 and 4) to determine the action, while the remaining four bits (from bitplanes 3-0) provide either a palette index or a 4-bit value for the modified channel.^[13] The encoding begins at the start of each scanline, where the initial "held" color is typically the background color from register COLOR00.^[6] For the first pixel, if the control bits are 00, it selects a base color directly from the 16-color palette using the four data bits as an index (values 0000 to 1111), loading the corresponding 12-bit RGB value from one of the COLOR00 to COLOR15 registers.^[13] Subsequent pixels process their six-bit value as follows: control bits 00 again selects a palette color, resetting the held color; control bits 01 modifies the blue channel by replacing its 4-bit value while retaining the red and green from the held color; control bits 10 modifies the red channel similarly; and control bits 11 modifies the green channel. This step-by-step propagation ensures that color changes are incremental and horizontal, with no carryover between scanlines.^[6] Mathematically, the color registers in HAM mode are 12-bit values formatted as 4 bits for red (bits 11-8), 4 bits for green (bits 7-4), and 4 bits for blue (bits 3-0). For a modify-red operation with data bits d (0-15), the new color register value is computed as:

\text{new_color} = (d \ll 8) \lor (\text{held_green} \ll 4) \lor \text{held_blue}

where \ll denotes left shift and \lor denotes bitwise OR; analogous formulas apply for green (

( \text{held_red} \ll 8 ) \lor (d \ll 4) \lor \text{held_blue}

) and blue (

( \text{held_red} \ll 8 ) \lor ( \text{held_green} \ll 4 ) \lor d

).^[13] Palette selection directly assigns

\text{new_color} = \text{COLOR}

.^[6] The horizontal adjacency requirement means modifications accumulate left-to-right along the scanline, with the held color updating only after each pixel is rendered, which can introduce visual artifacts such as banding in gradients.^[13] These artifacts arise because altering a single channel at a time cannot simultaneously adjust all three RGB components, often necessitating dithering techniques to approximate smooth transitions by interleaving modifications across adjacent pixels.^[6]

Palette Management and Bit Allocation

The Hold-And-Modify (HAM) mode on the Amiga utilizes a 16-entry color palette, where each entry consists of 12-bit RGB values with 4 bits allocated per channel (red, green, and blue), allowing for 16 possible base colors in standard operation.^[13] This palette is selected through a 4-bit index derived from the lower bitplanes, enabling direct access to one of the 16 predefined colors for non-modifying pixels.^[14] HAM extends the effective color range to 4,096 simultaneous colors without increasing the palette size, by dynamically altering components of the previous pixel's color rather than requiring additional palette registers.^[13] In HAM's 6-bit pixel representation, the allocation divides the bits across the six bitplanes as follows: the two most significant bits (from bitplanes 5 and 4) serve as control bits to determine the operation—00 for palette selection, or 01, 10, or 11 to select modification of the blue, red, or green channel, respectively.^[14] The remaining four least significant bits (from bitplanes 0 through 3) provide either the 4-bit palette index for hold operations or the 4-bit value to apply to the selected channel during modification.^[13] This structure leverages the Amiga's existing planar graphics architecture, where data from the blitter or Copper can populate the bitplanes without specialized hardware changes.^[14] HAM achieves memory efficiency by adhering to the Amiga's standard planar bitplane format, requiring no extra RAM beyond the six bitplanes needed for the mode—typically around 48 KB for a low-resolution 320x200 display, comparable to the allocation for 64-color standard modes.^[13] To prevent unwanted color propagation across scanlines, the mode resets the color state at the beginning of each line to the background color (register 0), ensuring horizontal modifications do not affect vertical continuity. Compared to standard Amiga display modes, HAM trades pixel independence for increased color depth: while a 16-color mode (using four bitplanes) allows each pixel to freely select from the palette without dependency on neighbors, HAM's 6-bit planes enforce sequential color derivation, enabling the full 12-bit color space within the same hardware constraints as higher-indexed modes.^[13] This approach maintains compatibility with the Amiga's 512 KB chip RAM limit in early models, prioritizing display quality over fully independent per-pixel coloring.^[14]

Original HAM Mode

HAM6 Specifications

The Hold-And-Modify (HAM) mode, known as HAM6 in its original implementation, is supported by the Denise chip within the Original Chip Set (OCS), introduced in 1985 for the Amiga 1000 and subsequent models. This hardware enables a 6-bit pixel depth configuration using six bitplanes for color encoding data, allowing the system to interpret pixel values in a specialized manner for enhanced color output.^[6] HAM6 operates at low-resolution (320 pixels wide) such as 320×200 non-interlaced or 320×400 interlaced for NTSC (60 Hz), with PAL variants supporting 320×256 non-interlaced or 320×512 interlaced at 50 Hz, or in HIRES (640 pixels wide) such as 640×200 non-interlaced or 640×400 interlaced for NTSC, and 640×256 or 640×512 for PAL; these dimensions align with the display capabilities of the OCS Denise, prioritizing color depth. The mode delivers 12-bit RGB color output, supporting a total palette of 4096 colors, though each pixel has 64 possible interpretations (16 palette colors plus 48 modifications), enabling up to 4096 unique colors across a scanline through sequential modifications and palette resets, without requiring palette changes mid-scanline.^[6] Activation of HAM6 requires setting bit 11 (HOMOD) in the BPLCON0 register to enable the mode, typically accomplished through Copper list instructions that dynamically manage bitplane pointers and color registers during scanline rendering; alternatively, software can invoke it via the Intuition library's OpenScreen function by specifying a HAM-compatible display mode ID. This setup ensures compatibility across all OCS-equipped Amiga models, including the 1000, 500, 2000, and 3000 series, as well as ECS variants up to the 4000 with ECS Denise, though true color continuity across different chipsets demands additional software intervention to maintain palette states.^[6]

Usage Techniques

To implement Hold-And-Modify (HAM) mode on Amiga systems, developers typically use Intuition's OpenScreen function with a NewScreen structure specifying six bitplanes for depth, combined with the SA_DisplayID tag to select a HAM-compatible display mode ID from graphics/modeid.h.^[15] Once the screen is opened, layers.library routines such as LockLayerInfo and InstallLayerInfoHook manage overlapping drawing areas on the HAM screen, ensuring proper clipping and compositing for multi-layered graphics.^[16] For low-level control, custom copper lists are programmed to set the BPLCON0 register (at $DFF100) with bit 11 (HAM) enabled and bits 14-12 (BPU) set to 101 for six bitplanes, often synchronized via WAIT instructions to activate the mode at specific scanlines.^[6] Optimization in HAM programming relies on strategies that mitigate the mode's horizontal color dependency, where each pixel's hue builds on the prior one. Horizontal dithering, such as ordered or error-diffusion patterns across adjacent pixels, simulates intermediate colors by alternating between base palette entries and modifications, enhancing perceived color depth in gradients without exceeding hardware limits.^[17] Palette animation via copper-driven updates to COLOR registers (DFF180-DFF1BE) enables dynamic scenes by cycling the 16 base colors per frame or scanline, creating illusions of motion or brightness shifts, as seen in effects like fading text blocks.^[18] To avoid vertical color jumps, developers plan scanline content in advance, resetting the base color at line starts through copper MOVE instructions to BPLCON0 and ensuring adjacency in pixel data preprocessing.^[19] HAM mode finds common use in static image rendering, such as converting RGB artwork from tools like Deluxe Paint III to six-bitplane HAM formats via dedicated utilities that optimize pixel adjacency and palette selection for minimal fringing.^[18] Simple animations, including scrollers or fades, leverage blitter operations for fast area fills and copies, where the blitter's line modes draw dense patterns across bitplanes to approximate shapes or transitions in HAM space.^[17] Early utilities like custom HAM converters preprocess true-color images by quantizing to 4096 colors and applying dithering, requiring manual adjacency checks to preserve horizontal continuity during import.^[19]

Limitations and Visual Artifacts

The original HAM6 mode imposes several key restrictions stemming from its horizontal color propagation mechanism, where each pixel's color is derived by modifying one RGB component of the preceding pixel unless a base palette color is selected.^[6] This dependency prevents fully independent pixel colors, as a modification to one pixel inherently affects all subsequent pixels in the scanline until a reset via a palette index occurs.^[20] Consequently, achieving distinct colors often requires up to three sequential modifications per base palette entry—one for each RGB channel—before necessitating a palette reset to avoid cumulative errors or unintended hues.^[6] These constraints manifest in notable visual artifacts, including Mach banding, where the discrete 4-bit steps for channel modifications create perceptible contours in smooth gradients rather than seamless transitions.^[6] Color bleeding is another common issue, particularly in gradients or complex images, as propagated modifications can spill unintended tints across adjacent pixels if resets are infrequent, leading to blurred or inconsistent edges.^[6] Additionally, the mode's incompatibility with straightforward scrolling exacerbates these problems, requiring full bitplane recalculation for any vertical or dynamic movement to maintain color integrity across scanlines.^[20] Performance impacts further limit practical use, with HAM6 confined to low-resolution modes (such as 320×200 or 640×200 pixels) and demanding higher CPU overhead for techniques like dithering to approximate smoother colors.^[6] Interlaced displays introduce flicker, as the alternating fields amplify propagation inconsistencies over time.^[6] True high-resolution HAM requires bitplane slicing, which compounds these demands without native hardware support.^[6] While workarounds such as dithering can mitigate some artifacts by blending modifications across pixels, they do not fully eliminate banding or bleeding and increase computational load, rendering HAM6 unsuitable for fast-motion applications like games where real-time recalculation would overwhelm the 68000 processor.^[20]

Advanced Implementations

AGA HAM8 Mode

The Advanced Graphics Architecture (AGA) chipset introduced Hold-And-Modify 8-bit (HAM8) mode in 1992 alongside the Amiga 1200 and Amiga 4000 computers, leveraging the Alice chip for enhanced memory control and blitter operations. This upgrade enabled 8-bit pixel depths to generate up to 262,144 colors from an 18-bit RGB space, supporting resolutions like 640×200 at 60 Hz or 640×256 at 50 Hz, significantly expanding visual fidelity beyond prior modes.^[21]^[22] HAM8 improves upon the original HAM6 by utilizing two control bits per pixel to select either a hold operation (sampling from the palette) or a modify operation on the red, green, or blue channel of the preceding pixel, with the remaining six bits providing 64 discrete levels per channel for more precise color transitions and fewer banding artifacts in gradients.^[22] This finer granularity allows up to 262,144 colors (18-bit RGB) in high-resolution interlaced or non-interlaced modes, such as 640×400 or 640×512.^[23]^[21] Technically, HAM8 operates with 8 bitplanes activated alongside a dedicated mode flag in the chipset registers, drawing from a 64-color base palette selected from the 256-entry 24-bit palette (though HAM8 effectively yields 18-bit output per pixel).^[22] Backward compatibility with HAM6 is maintained by limiting palette access to the first 16 or 64 entries and emulating 6-bit pixel behavior, ensuring legacy software rendering without modification.^[22] In applications, HAM8 found use in late-period Amiga games and demos, enabling smoother color gradients for complex scenes like textured environments or photographic imports that benefited from the mode's reduced artifacts compared to HAM6.^[22]

Other Variants (HAM4, HAM5, HAM7, SHAM)

HAM5 represents an experimental reduction of the standard HAM6 mode, employing only five bitplanes to conserve memory in scenarios with constrained resources, such as early prototypes or applications requiring faster rendering on OCS/ECS hardware. In this variant, the sixth bitplane is fixed to zero, limiting color modifications to the blue component alone, as the mode selection bits are derived from the fifth and fourth bitplanes. This results in lower color fidelity compared to full HAM6 but enables 32 possible colors without the full palette overhead, though visual quality suffers due to restricted RGB adjustments.^[19] HAM7, a variant on OCS/ECS systems, leverages a seven-bitplane setup as a hack to achieve HAM functionality with reduced DMA overhead. By requesting seven bitplanes, the hardware activates only four via DMA while using copper instructions to supply constant data to planes five and six (e.g., alternating RGB patterns like $RGBGRGBGRGBGRGBG for targeted modifications). This enables selective RGB tweaks for effects like ghosting or dithering, demonstrated in demos such as "HAM Eager," where it supports 4096 colors in constrained windows but defaults to 16 indexed colors elsewhere. The mode exploits undocumented OCS/ECS behavior, where planes five and six repeat static values without DMA, facilitating efficient chunky-to-planar conversions or blitter operations.^[17]^[24] SHAM, or Sliced HAM, emerged in the early 1990s as a software-driven technique by third-party developers, including NewTek for tools like DigiView 4.0, to mitigate HAM artifacts through per-scanline palette slicing. It interleaves standard HAM encoding with custom copper lists that redefine 15 of the 16 palette registers every line, creating 256 unique palettes across a 320x256 screen for pseudo-high-resolution output. This brute-force optimization tests all 4096 HAM colors per entry to minimize perceptual errors, maintaining computational parity with single-palette HAM while vastly improving gradient smoothness and reducing fringing. Though effective for still images and video capture, SHAM saw limited adoption post-AGA due to its complexity and incompatibility with faster hardware modes, often requiring NTSC tuning that underperformed on PAL systems.^[25] These variants share core HAM traits—software-managed via copper for dynamic palette shifts and bitplane control—but emphasize trade-offs in precision, memory, and resolution for specialized uses like demos or legacy tools. Their unofficial nature confined them to enthusiast circles, with implementations relying on chipset quirks rather than standard documentation.^[17]

Emulations and Modern Applications

Software Emulations

Software emulations of the Hold-And-Modify (HAM) mode enable the recreation of Amiga graphics on contemporary non-Amiga systems, primarily through cycle-precise simulations of the Original Chip Set (OCS) and Advanced Graphics Architecture (AGA) chipsets. Emulators like WinUAE and FS-UAE, both derived from the UAE codebase, fully support HAM rendering by accurately modeling the hardware's pixel modification logic and palette operations.^[26]^[27] These tools achieve high fidelity by emulating the exact timing and behavior of Amiga video hardware, allowing HAM6 and HAM8 modes to produce the characteristic 4,096 and 262,144 color displays, respectively, while adhering to original constraints like the 12-bit color depth.^[26] To enhance visual authenticity, these emulators incorporate pixel shaders, typically OpenGL-based, for post-processing effects that mimic period-accurate display characteristics, such as scanline rendering and subtle color artifacts from phosphor persistence. FS-UAE's shader system, for instance, loads custom GLSL files to apply filters that replicate the Amiga's analog output without altering core emulation accuracy.^[28]^[29] WinUAE similarly supports shader integration for CRT-like effects, ensuring that HAM's hold-and-modify transitions appear as they would on vintage monitors.^[30] Deployed on PCs across Windows, Linux, and macOS, these emulators facilitate seamless HAM playback for legacy software and demos. HAM emulation extends to mobile and web platforms via UAE derivatives. On Android, ports such as UAE4Droid provide OCS/AGA support, including HAM modes, though performance varies with device capabilities.^[31] Browser-based solutions like the Scripted Amiga Emulator (SAE) run in JavaScript and HTML5, emulating HAM through WebGL rendering for interactive web demos of Amiga content.^[32] Image conversion tools complement these emulations by translating modern RGB graphics into HAM-compatible formats. The Java-based ham_convert utility, updated to version 1.12.0 in August 2025, uses brute-force search to optimize pixel mappings, producing high-quality ILBM IFF files in HAM6, EHB, and other modes while reducing common artifacts like color banding.^[33]^[34] This cross-platform tool processes inputs from formats like PNG and JPEG, enabling creators to generate authentic HAM visuals for emulated environments.^[35] Despite these advances, software emulations encounter hurdles in real-time execution on resource-constrained hardware, where cycle-precise OCS/AGA simulation demands significant CPU overhead, often mitigated by just-in-time (JIT) compilation but still lagging on low-end devices.^[36]^[37] Preserving HAM's inherent visual artifacts—such as edge fringing from sequential color modifications—poses another challenge, requiring precise shader tuning to avoid over-correction while maintaining historical fidelity.^[29]

Hardware and Third-Party Implementations

One notable hardware extension for HAM was the Black Belt Systems HAM-E and HAM-E Plus, released in 1991 as external framebuffers connecting via the Amiga's RGB port. These devices supported an extended HAM mode that achieved 18-bit color depth from 8 bits of data through compression techniques, building on the original HAM principle but with reduced pixel-level control compared to native modes. The HAM-E offered resolutions up to 384×560 in overscan, while the HAM-E Plus doubled that to 768×560 and added hardware antialiasing, making it suitable for professional image processing and compatible with tools like NewTek's DigiView buffers.^[38] The NewTek Video Toaster, a Zorro II expansion card introduced in 1990 for Amiga 2000 and later models, integrated HAM modes into broadcast video production workflows. Its software interface, including ToasterPaint, utilized standard Amiga HAM screens to handle 768×400 virtual canvases while maintaining internal 24-bit data for editing, enabling effects like chroma keying and transitions on digitized footage displayed in HAM. This hardware-software combination powered low-cost TV graphics in the 1990s, with the Toaster 4000 variant in 1993 leveraging AGA's HAM8 for enhanced color fidelity in professional setups.^[39]^[40] In the 2010s, the Apollo-Core Vampire boards provided modern hardware extensions for classic Amiga systems, incorporating FPGA-based 68080 CPUs that supported full AGA chipset emulation, including HAM8 mode extensions for up to 256,000 colors. These accelerator cards, compatible with Amiga 1200 and 4000 models, accelerated rendering of HAM-based content through integrated IDE, HDMI output, and chipset replication, allowing legacy video tools to run at higher speeds without altering display artifacts. Similarly, the MiSTer FPGA platform's Minimig core, developed from 2017 onward for DE10-Nano boards, delivered cycle-accurate OCS/ECS/AGA emulation with precise HAM timing to preserve original scanline behaviors and color hold-modify sequences.^[41] During the 1990s, HAM found commercial application in Amiga-based video production tools beyond the Video Toaster, such as Black Belt's HAM-E for frame grabbing and effects compositing in broadcast environments. These implementations enabled cost-effective creation of visual effects for television, including color-cycled animations and digitized overlays, by exploiting HAM's high color count on limited hardware bandwidth.^[42]

Recent Recreations and Legacy Uses

In 2025, the X65 project implemented a variant of the Amiga's Hold-And-Modify (HAM) mode on an 8-bit MOS 6502-based FPGA system, adapting the technique for retro gaming applications on resource-constrained hardware. This port simulates a 6-bit HAM mode using assembly language, encoding each pixel with 3 bits for base color selection from an 8-color palette and 3 bits for modification commands (hold base, red delta, green delta, or blue delta), with bitpacking to fit four pixels into three bytes for efficient 24-bit processing. The implementation operates at 320x240 resolution to stay within 64 kB memory limits, incorporating a blend command for smoother gradients via 50/50 color mixing and 1/32 quantum deltas to approximate Amiga's 12-bit color depth on 8-bit hardware, enabling display of high-color images in retro gaming contexts like demoscene-style visuals.^[3] Recent software tools for HAM processing saw updates in 2025, with ham_convert version 1.12.0 released in August, enhancing image conversion for Amiga-compatible formats through higher-quality resizing algorithms and expanded input format support, including improved brute-force optimization for HAM6 slicing to minimize color errors in modern image processing workflows. This update facilitates cycling palette animations by better handling dynamic color reductions, allowing users to generate ILBM files suitable for emulation or hardware rendering with reduced artifacts in gradient-heavy scenes.^[43]^[44] HAM principles continue to influence Amiga demoscene revivals, as seen in 2024 YouTube-hosted compilations of new demos like those from Revision 2024, where groups such as Darkage and Spreadpoint incorporated HAM-derived color techniques in AGA-compatible productions to evoke 1980s aesthetics with modern twists, such as interlaced 4,096-color effects in static or low-motion sequences. Educational recreations have also proliferated, with 2025 forum discussions and video tutorials demonstrating HAM's mechanics using contemporary tools to explain 1980s graphics limitations, often converting modern photos to HAM for classroom or online learning about early compression methods.^[45]^[46]^[47] Beyond niche revivals, HAM's hold-and-modify approach inspires compressed graphics in embedded systems, exemplified by the X65's memory-efficient pixel encoding that achieves 4096-color simulation on 8-bit processors without full palette expansion, offering lessons for low-power devices in 2025 IoT applications. Online forums in 2025 have highlighted HAM's efficiency—requiring only 6 bits per pixel for high-fidelity gradients—contrasting it with modern GPUs' delta color compression (DCC) techniques, noting how Amiga's hardware-level modifications prefigured bandwidth-saving methods in AMD and NVIDIA architectures without the overhead of programmable shaders.^[3]^[48]

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[27]
WinUAE Amiga emulator
Jul 3, 2025 · WinUAE is an Amiga emulator. Version 6.0.1 includes bug fixes, and 6.0.0 has a major update to custom chipset emulation.Download · Basic features · WinUAE 5.3.1 · WinUAE 5.3.0
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FS-UAE Features
FS-UAE is an Amiga emulator for Windows, Linux and Mac OS Xbased on UAE/WinUAE, with a focus on emulating games, though it also emulates high-end Amigas.Missing: HAM | Show results with:HAM
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shader | FS-UAE
The shader option in FS-UAE is an OpenGL pixel shader. It can be a bundled shader name or a path to a shader file. Default is 0.
[30]
Achieving period-correct graphics in personal computer emulators
Apr 15, 2022 · In this article series we'll be looking at emulating the Commodore Amiga, Commodore 64, and MS-DOS/early Windows era IBM PC compatibles with period-correct ...Missing: HAM | Show results with:HAM
[31]
Achieving period-correct graphics in WinUAE - AmigaLove
Apr 24, 2022 · I've recently discovered a method to emulate the C= 1084S quite faithfully in WinUAE via shaders, so I wrote a lengthy blog post about it.Missing: FS- UAE<|separator|>
[32]
Amiga Emulator for Android | XDA Forums
Dec 21, 2009 · Hi folks, I spent a good part of my sunday (and friday night, let's be honest) to port UAE4All for Android. So here's UAE4Droid.
[33]
Scripted Amiga Emulator: SAE
This site is the home- and demopage of the SAE, an Amiga emulator in pure HTML5 and JavaScript. It is heavily based on WinUAE and does use the AROS-Kickstart ...Missing: HAM | Show results with:HAM
[34]
gfx/conv/ham_convert.zip - Aminet
Apr 9, 2025 · Its main use is to produce high-quality hold-and-modify (HAM) images using brute-force search. It can produce ILBM IFF files (Amiga graphic ...
[35]
Java-Programm: ham_convert 1.12.0 - amiga-news.de
Aug 24, 2025 · Sebastian Sieczko's Java-based program ham_convert converts modern graphic formats into the HAM format of the Amiga. ... Copyright © 1998-2025 by ...
[36]
ham_convert | techno kanciapa - bplaced
Its main use is to produce high-quality hold-and-modify (HAM) images using brute-force search. It can produce ILBM IFF files (Amiga graphic modes: EHB, HAM6, ...
[37]
Help with Amiga emulation speed, please - Page 1
Jul 3, 2016 · That slowness is because of emulating without JIT. A quick test on my setup is showing Sysinfo mips drop 80% and mlops drop by 92% without JIT.<|separator|>
[38]
What makes accurate emulation of old systems a difficult task?
Apr 25, 2019 · A substantial amount of these emulators are hardly accurate when compared to the original hardware they are trying to emulate.Missing: HAM | Show results with:HAM
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Black Belt Systems HAM-E & HAM-E Plus - Amiga Hardware Database
extended HAM mode: similar to the normal Amiga HAM mode; uses compression techniques to achieve 18 bit colour form 8 bits of data; diminishes precise control ...<|control11|><|separator|>
[40]
NewTek Video Toaster - Amiga Hardware Database
the interface uses a standard Amiga screen in HAM mode, 768×400 is achieved as a virtual canvas; image information is maintained inetranally as 24 bit data and ...
[41]
A history of the Amiga, part 9: The Video Toaster - Ars Technica
Mar 18, 2016 · In 1993 NewTek released the Video Toaster 4000, an updated version that made use of the new AGA graphics hardware available with the Amiga 4000.<|control11|><|separator|>
[42]
The Big-box Amiga Vampire 68080 Accelerator Guide - Amitopia
Feb 8, 2021 · You can purchase a Vampire CPU board for Amiga 2000. But as you see in the video, it fits well. ArenaNet also made an Amiga 2000 CPU adapter ...
[43]
Full text of "Amiga World Special Issue: 1990 Video and Animation"
... Amiga as a video- editing tool. In a recent survey, the Amiga had already ... For this reason I tend to think of HAM paint programs primarily as tools ...
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May | 2025 - techno kanciapa
May 1, 2025 · ham_convert 1.11.1 ... New in this version: higher quality resizing, more supported input formats, MSX2+ screen 10 yjk+palette conversion.
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Java program: ham_convert 1.11.1 - amiga-news.de
May 3, 2025 · Sebastian Sieczko's Java-based programme ham_convert converts modern graphic formats into the Amiga's HAM format. Changes in version 1.11.1 ...Missing: RGB | Show results with:RGB
[46]
https://www.youtube.com/watch?v=ZQkn7Qwz0Qg
[47]
Depeche's Mode Demo by Spreadpoint - Revision 2024 ... - YouTube
May 13, 2024 · Depeche's Mode Demo by Spreadpoint - Revision 2024 Amiga Demo Compo. 478 views · 1 year ago ...more. Revision Captures. 1.86K. Subscribe.Missing: HAM | Show results with:HAM
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Amiga 2025 tech
May 2, 2025 · Also think of HAM: How todays digital photo and powerful software can convert and tweak HAM pictures to superior quality. Data compression ...
[49]
HAM/HAM8 limits - Amigaworld.net
Sep 8, 2025 · Amiga AGA can do pre-baked full motion HAM8 laser disc-style games. The problem is the Commodore's weak game content to drive platform sales for ...