How the Amiga's HAM Mode Worked - 4096 Colours in 1985

[@gregatim]

I'll tell you, I'm astonished, first by the fact you're giving both pixel art and amiga tutorials and explanations for free, second you rarely even pass 1000 views showing that you don't care about views. second. you really are a good artist, and the fact, you use Amiga to make art (too, I know you're talent more than just pixel art on amiga) shocks me even more. I never saw any amiga art, and seeing this first time shows how a 1985 pc can still surprise someone like me, a person that saw all the types of art; hand-drawn, oil drawing, digital, ASCII. etc(not something to be proud of, it just shows I spend my time looking and overlooking a drawing for no reason other than I'm interested way too much in art ) it's impressive what you can do with an Amiga, to be honest. 3:12 for example, look at that sky, that village, those mountains, those Japanese kana in the right down corner. it's way too much detail for a 342x70.

[@vix_in_japan]

Thank you, that's been one of the very nicest things anyone has said to me on KZbin. I'm glad you appreciate the artistic side of this, as I'm moving the channel much more in that direction (although occasionally bringing in the older retro tech like the Amiga into the artwork). Yes I've been pretty small time but I've always felt it more important to cover topics I am interested in and have passion for rather than chase views; my artwork is my main focus and sense of direction, being a KZbinr is just a way of expressing that, and will as such always come second. My next video will be showing more of the Amiga in use in concert with hand drawn character and background art but how my processes allow me to use that artwork in different mediums :) Thank you again for those kind words.

[@simonebernacchia5724]

Hmm, Ataru Moroboshi in the Avatar, isn't that coincidential? ;)

[@10MARC]

What a fantastic video and explanation! I need to rewatch it a few times for sure. HAM Mode is one of my favored modes to work in as I normally like to do Photo editing. I am still so impressed with how HAM6 holds up even today. Thank you for the Shout Out, too! I appreciate it.

[@vix_in_japan]

Thank you Doug, yes it was hard getting that explanation to make sense and not take too much time doing so. Hopefully a few watches all will become clear :)

[@jjdigitalvideosolutionsllc5343]

Good video. If you do an updated version, you could include Sliced-HAM displays. For improved HAM animation results, we used to render 24bit images in Imagine 3D, then process those into HAM6 with ImageMasterRT. Then frames were then compiled in Anim7 format. Further, we used a letterboxed resolution for the cinematic feel. The reduced vertical resolution, helped speed up animation platyback more.

[@vix_in_japan]

I did wonder about sliced HAM but it's not technically a mode, more a HAM screen with further copper list manipulation but yeah, I should have mentioned it really. Sounds like you had a very cool process using HAM! Back in the VHS recording days, HAM's artifacts often got blended, and these days I just embrace its quirkiness, as it's fun!

[@jjdigitalvideosolutionsllc5343]

@@vix_in_japan I was just thinking that HAM fringe remind me of lens aberration that you sometimes see along edges of objects in photos. Sliced-HAM and Dynamic-HiRes were palette changing techniques that produced some really stunning images. I don't think any paint programs supported these modes. It'd be nice to see Hyperion add these modes as options to an OS3.2.x update for displaying images on OCS/ECS systems.

[@ArneChristianRosenfeldt]

If we show animations on 50p or better 60p and a pixel changes color over time, we can select the exact frame where it jumps to the next palette entry. So animations should feel colorful even on the ST.

[@madigorfkgoogle9349]

@@ArneChristianRosenfeldt Animations on ST actually look a lot more colorful then HAM6.

[@ecernosoft3096]

. . . Because I am shattered at how well you have explained this, you have earned another subscriber.

[@vix_in_japan]

You're welcome and I hope you enjoy the randomness of things here!

[@ecernosoft3096]

@@vix_in_japanAtari was awesome in 1985 when they (under the commodore brand) put out this awesome, 16 bit sequel to the 8 bit A8.

[@andreafluffkitten]

How did I miss this? Good video Vicky.

[@vix_in_japan]

Thanks Andrea, I think this was the last video I put out before the move to Japan if I remember right!

[@trydowave]

listened to this at work and even though i couldn't see the video i found it very interesting. You're an excellent communicator :)

[@marmeladenfreund]

Thanks for the great and well understandable and sound video! It brings back fond memories of my teenage years with my Amiga in the 1980s. It was not only a powerful gaming computer, but my first truly capable, flexible digital multimedia creative tool. I used the Amiga to create graphics (pixel art and ray tracing), make music, and program/code (demos). I have to admit, though, that I was never too big a fan of the HAM6 mode. Although at the time it was truly amazing to see digitized photos on an affordable home computer for the first time in history (computers that could do this back in the mid-80s, pre-VGA days, were usually high-end professional graphics workstations that were completely out of reach for average people), from my point of view, using HAM mode was very bulky, complicated and involved too many compromises. Personally, I preferred to work with EHB, Copper-Tricks and Sliced-Mode to get considerably more than 32 colors on the screen without annoying color-fringing. Unfortunately there were nearly no standard tools for this, you mostly had to build/program your own workarounds. Considering the for today limited 12-bit/4,096 color palette (which was of course a lot back then) based on 16 RGB gradations each, photos or photorealistic images of course never used the full color palette of the Amiga, but only a fraction of it - and some of these colors were even HAM-fringe colors on top of that. I recently allowed myself the fun of using an image processing program to simulate how many colors digitized photos actually have in a 12-bit color space. To do this, I first reduced the resolution, then split the RGB channels of the images, simplified each to the exact 16 gradations of the Amiga, and then merged them back together. This somewhat awkward "mathematical" approach based on the third root is necessary because common image processing programs can only handle 1-256 colors or 24bit true color and can not simulate a 12Bit space. I tried this on 20 very different images (various photos, artwork, visualizations). The number of individual colors was usually between 150 and 300 per image. Only one image (a garish jungle artwork with lots of rainbows, colorful flowers and exotic animals) reached almost 1000 colors. Therefore it is a pity that the 2nd generation of Amigas from 1987 on did not come with a standard 256-color mode. It would have been sufficient for most images within the 12-bit color space of the Amiga and would have been far superior to the HAM in speed and usability... (A HAM8 could have been available additionally...)

[@vix_in_japan]

Wow that sounds impressive. Yes it's a shame there wasn't a package for making sliced HAM or essentially copper list driven painting programs but there you are. HAM mode for me is more interesting for making use of those strange fringe artifacts for glitch artwork; but yes some HAM conversions can look quite ugly! Some look impressive still though for the tech. As for the 256 color mode, couldn't agree more. Commodore really screwed the pooch on that; the Mac II had that ability come 1987; and many Amiga owners will say yes but it was expensive. And they're right; but, it could do it! It was a premium thing, flicker free 640x480 in 256 colors in 1987. If cost was the only thing that mattered to people, why is the Mac still around and the Amiga not (it a full proper commercial in retail sense that is.) Unfortunately so much of the reason is intertwined with Amiga OS being so intrinsically linked to the custom chips that they had to almost move in lockstep. And as innovation on both was stifled, so was the Amiga as a whole.

[@ecernosoft3096]

Late note- The amiga can do overscan. So really, on NTSC, it can do up to 352x240 (non interlaced) or 352x480 (interlaced). But it would rarely be used since you’re using more DMA. In hires this would be up to 720x480, or 720x576 for PAL. That’s DVD quality! Well… minus the fringing.

[@ArneChristianRosenfeldt]

So what you really say is that we need HAM4, which would need no DMA?

[@ecernosoft3096]

@@ArneChristianRosenfeldt No, what I'm saying is that HAM8 on Amiga AGA systems can reach DVD resolutions, and would be quite the sight in 1991.

[@ArneChristianRosenfeldt]

@@ecernosoft3096 yeah, memory technology advanced enough to give us a framebuffer for TVs. It is just that “hold and modify” is a dead end.

[@madigorfkgoogle9349]

@@ArneChristianRosenfeldt what he said is that Amiga has just 4 DMA channels reserved for Denise, which means 4 bitplanes only, aka 16 colours. If you want more bitplanes, you have to take away a DMA channel from something else, usually CPU. Which means 32 colours is 5 DMA channels and HAM6 is 6DMA channels. That is why Amiga is very slow using HAM6, and also why majority of fast paced games uses 16 colours only. DMA means Direct Memory Access, that means that the particular chip of chipset can read the data from ChipRAM address directly. Otherwise all the data would have to be painfully red by CPU from ChipRAM and written to Chipset Chip register directly by CPU, step by step. That would slow down Amiga hugely.

[@ArneChristianRosenfeldt]

@@madigorfkgoogle9349 yeah, I paraphrased OP and cut some words out. I learned that Amiga in contrast to ST can give the CPU memory access every second cycle. The 68k can access memory every other cycle, but most instructions let it access memory every fourth cycle. With a given DMA channel rhythm, there should already be a difference between 2 and 4 bitplanes? It would be great if the CPU could announce in advance when it needs the memory so that we shift the access which are buffered anyway. Like, there is a deadline until all but planes need to have been read, but the exact cycle is not important.

[@naviamiga]

Great guide. Excellent use of Ranma 1/2 images too.

[@vix_in_japan]

Thanks! Always good to have some Ranma fandom :)

[@RoboNuggie]

Excellent explanation. Thank you very much for making this.

[@vix_in_japan]

Thank you! It was a complex one to distil, especially as I’m not a computer scientist so may use the wrong terminology but I do understand it in my own quirky way!

[@Error42_]

I remember first playing around on my Action Replay with bitplanes where you could scan the memory for graphics and switch the modes. The whole bitplanes way of doing things seemed a bit crazy to me when I first saw it. I think I expected it to be more like how a PC would work, not that I had the knowledge to know that at the time. But when you got all the bitplanes aligned with the Action Replay on a frozen game and got to see all the sprites it was like finding gold :-) Thanks for the explanation. EHB makes more sense when referenced to the idea of a whole bitplane to switch between the half bright and normal colour on a per pixel basis. I was still just thinking of this as a bit mask on a byte by byte basis. Some PC modes used 16 bit, I think they had 5 bits per channel for RGB and an extra bit went on one of the other colours. I think it was green that had the extra bit because we can see more variants of green than red and blue... I'm sure you'll tell me if it's red or blue though being the photographer :-) HAM mode is pretty nuts really. I mean, who would even think of this as a concept. I think that's what differentiates the sort of people that designed the Amiga from everyone else, to them it probably wasn't really all that nuts. The colours in that Tokyo scene are so vibrant.

[@vix_in_japan]

That's so cool, I never had an Action Replay but I later learnt that is how eventually Amiga magazines did screenshots for games although I have a soft spot for the old magazines where it's clearly a photograph! Glad you found the video helpful :)

[@TheRetroShed]

First time I ever played with HAM mode I think was with a copy of Photon Paint back in the day...

[@vix_in_japan]

That's a fun application :)

[@TheRetroShed]

Pixel Vixen remember that one?!

[@vix_in_japan]

@@TheRetroShed Yep I still own it and occasionally use it, I got it with my Amiga 600 from Silica :)

[@NightSprinter]

Olan Mills.. I feel old, now.. Made me think of various outings to Sears for family photos (as they set up a photo center by layaway).

[@tiannaumann]

10marc's mention of you in his latest youtube upload (Apr. 12/21) brought me here. :)

[@vix_in_japan]

Hope you enjoyed the video and nice of Doug to mention me.

[@PlayBASIC-Developer]

Great explanation..

[@vix_in_japan]

Thank you!

[@gavinguy148]

Great video. I have a much better understanding and appreciation for it. Thanks. Good like with the move.

[@vix_in_japan]

You're welcome and thank you!

[@TheOneTrueSpLiT]

I used Deluxe Paint III on my A500 to produce a presentation video for my Computer Science HND final project. It was mainly static diagrams but some "slides" used animation to show data flow in the system and a pseudo-chrome project logo done in HAM mode. I passed that part of the course with flying colours thanks to my lecturers being amazed by the presentation and, despite only having had said A500 for 6 months, I part exchanged it soon after that presentation for an A2000 (which I still have) and bought Real3D Pro with which I re-created many Pixar characters (Tin Toy, Red's Dream, Luxor Jnr) and took a "portfolio" of HAM images to a computer graphics show at Olympia to show some companies in an attempt to move into CGI as a career, but that never happened. My A2000 was heavily upgraded at the time (1991) with a GVP 68030+68882 and OpalVision and I also re-created a few scenes from Terminator 2 (which had just been released at that time) demonstrating the liquid-metal T-1000, so until OpalVision with 32Bit graphics came along all my CG work was done in HAM mode with the exception of some 16 colour sprites I did for games that used "clever" use of those limited bit-planes to imply more colours ;) As I said I still have the A2000 as it was back in the 1990s along with all the disks for Deluxe Paint, Photon Paint, Sculpt4D, Real3D etc. but alas it won't power up :(

[@Mark-pr7ug]

Thanks for explaining. I tried ham mode with paint but the colour shifting put me off. Deluxe paint is still sadly missed x

[@vix_in_japan]

It's something more designed (if I can use that word) for composite video or similar output, RGB or displaying on a big display these days just highlights flaws so much and in some instances that fringing is a doozie. But on a small CRT on composite, with the right image and the right software, it can be impressive to see a 68000 Amiga chuck out a HAM image with a blitter object or two animated over the top of it. But yeah, I don't use HAM that often myself.

[@Mark-pr7ug]

@FutureSaviors yes, at times I miss the old CRT. On one of those screens, dithering or pixel stipling blended perfectly providing of course that you balanced the rgb of the two colours in question. Regarding HAM mode:- I believe there was(back in the 1990s) a computer game in progress which was supposed to be using it. It was supposed to be a platform styled game, however it never came to be.

[@KabelkowyJoe]

Thanks for explanation, 13:35 what came to mine mind is Microsoft ClearType and fact that color screens both CRT and LCD are arranged as arrays of RGB "sub pixels" so it's wrong to start with green if you have RGB "sub pixels" would be better if in HAM mode to translate from black to white we modify Red then Green then Blue we end up having White but three pixels being slightly more redish then green then blue would make from bigger distance one pixel of White just or almost just as ClearType Microsoft patented way to make anti aliasing of fonts. From bigger distance this three sub pixels would look more whiteish. I just cant imagine this on fly maybe its correct to start with green but.. i just noticed that HAM is not only great idea to simplify graphic adapter, to compress data its precursor to that UV color spaces of TV screen, its precursor to ClearType kinda even these days used to make DVI and HDMI limited bandwidth make it possible to show higher resolutions at cost of colour. So nothing really changed since 1985. Im interested in this because im trying to make GPU for old systems like PC using simple uC and limited memory. Wont write details of mine "patent" but HAM is.. is genious idea to simplify logic and DAC.. I love it, it's just mind blowing how ingenious it was. Mine hobby was also data compression, long time ago, so happened first compressor "by accident" was compatible with NTFS data compression LZ77 4096 it's magic number. Thanks to hash chain speeds up. So happened L1 cache in most CPU best fits with 4096 dictionary, it's 16-32kB so entire dictionary can fit into L1 cache. Also 12bit for offset plus 4 bit for lenght is "optimal" for LZ77, here we have 4 bits for register number, 4096 colours, 4 bits for "control bits" up to 6 bits total.. i see that even this days 4096 is when all magic happens.. and im amazed. Amiga was also that place where most of compression methods was developed. Most of ideas we use these days maybe except ANS - Asymetric Numeric Systems was actually developed on Amiga on 68k PC users stuck with ZIP all that time, stuck with 16 colors, for long time.. decade is a looong time..

[@DanielMonteiroNit]

More like this, please :D

[@vix_in_japan]

Thank you for the feedback! I’m so happy this video was enjoyed :)

[@one_b]

HAM was mind-boggling to try to understand as a 10 year old with no internet to be able to look things up. This was a great explanation. It is too bad that some alternative memory maps for graphics weren't available. Bitplanes only make sense to me as a means to work around memory constraints of the time while still having a really large palette for the time. They can also produce some interesting effects when shifted around (State of the Art demo anyone...) or with HAM but a 32 color screen needs 5 bytes written to change one pixel. (And 6 for 64EHB, etc..) Blending colors takes 5 reads and writes... This is no good for plotting points, drawing lines or other primitives, and polygons. One "back of the napkin" memory map alternative I made reduces this one or two bytes to change any one pixel, still be 32 or 64 colors in low-res, and insignificantly more memory. (Of course the logic would have been more complicated to encode/decode.) I like to imagine what it might have been like if the ECS/OCS Amiga had more than double the pixel fill rate right from the start.

[@vix_in_japan]

That's some very interesting thoughts, but you are right this is very much about saving memory. Confidential documents recently revealed by the Commodore International Preservation Society (I think that's right) even show in late 1985 Jay Miner and Commodore were convinced that the Amiga's bitplane graphics were a dead end and chunky pixels were the way forwards.

[@one_b]

@@vix_in_japan That is very interesting to find out. It makes me wonder what drove them to continue in the direction they did for so long after? It is just too tempting to think management within Commodore was inept but it seems to be a recurring theme.

[@valenrn8657]

@@vix_in_japan VGA has both chunky and bitplane modes, hence Amiga chipset could have evolved with chunky support e.g. Vampire 500 2+

[@Koseiku]

pixel vixen: yeah around here we draw pictures but first some computer science me: mhh ham :^)

[@wilsonnw]

Subbed. Turns out I have a Non EHB machine. Curious to know if many games use EHB or HAM

[@vix_in_japan]

Thank you! I hope the video was helpful. You must have an early A1000 not to have EHB.

[@wilsonnw]

@@vix_in_japan I think so. It's a Silvertop Denise chip, not black. 512k NTSC 1000. I have a 2mb sidecar for it, but have not tested that yet.

[@evgenius123_]

I thought, is it possible to increase the colors on the screen by quickly switching the colors of the screen palette during the rendering process in order to get more colors in total? Typically this technique is used for vertical gradients and animations.

[@skuula]

Call me ignorant, but how did you take digital photos with a Nikon FM - it's a film camera isn't it? Scanned the film , or is there a digital back for it?

[@vix_in_japan]

When the film was processed I had scans made by the lab (Canadian Film Lab)

[@AmstradExin]

I found it kinda sad....The OCS Chipset was capable of showing 256 colors....But they couldn't squeeze the color registers into what became Denise. This was found out during production. And HAM was some kind of stop-gap solution. Instead, it became a marketing tool and the EHB mode was later slapped on. Later, coders used HAM mode as a fill mode for flat polygons. Just like the blitter technique. As an alternative.

[@vix_in_japan]

Thank you for your comment. I'd be interested to hear or read where you found this out from as I have never heard of OCS having 256 colour registers, or HAM being a stop gap -- that is often cited as being Jay Miner's creation because of his interest in flight sims but HAM was almost removed as it was "too slow". Likewise not familiar with using HAM mode being used as an alternative to the blitter's area fill capability, although I guess they hold the previous pixel's value but don't actually change the colour channel value relative to the pixel to the left I guess?

[@valenrn8657]

The Copper can switch about 31 to 32 color (5 bit) registers per scanline on a regular 320 x 256 display. In EHB mode, copper modifies the upper 32 colors of the palette (they are darker versions of the lower 32 ones), hence this means Amiga OCS/ECS can theoretically display 256 * 64 distinct colors without the HAM method. For example. the game Pang uses this technique and there's an article from CodeTapper: www.codetapper.com/amiga/maptapper/documentation/gfx/gfx-palette Copper usage with a 5-bit color register and 5 or 6 bitplanes conserve the transistor budget and memory bandwidth respectively. Like Pang, the game Universe for Amiga OCS/ECS game also has 256 different colors. 256 colors with an 8-bit color register and 8 bitplanes will need a higher transistor budget and memory bandwidth. Since 1987, the Amiga Rander chipset has a 128 color register with 7-bit planes and faster VRAM. en.wikipedia.org/wiki/Amiga_Ranger_Chipset Amiga Rander has 4096 color palette (12 bits). Amiga 3000 with higher 32-bit chip ram bandwidth was wasted with ECS.

[@valenrn8657]

Amiga's Agnus chip has the ability to accelerate line draws and fill polygons independent of HAM mode. Agnus chip is the 2D accelerator.

[@ArneChristianRosenfeldt]

@@vix_in_japanprobably originally they used off-the-shelf SRAM , but then had to use Commodores aging fab. The fab could produce TED with 80 bytes of cache and 8 palette entries ( also bytes). But already TED lost the sprites to the fab.

[@gonegahgah]

I always wondered if they couldn't do a HAM mode that worked with HSV in place of RGB. I wonder how that would appear?

[@TheFusedplug]

Amiga used in the right way can still kick a PC's "a" Even AGA tech is 30 years old now but given some whopping CPU from today I bet some amazing results could be achieved with HAM 8 mode - one day a HAM 8 based game perhaps? I'd love to see that

[@ArneChristianRosenfeldt]

I did not understand why true color came to CDi early, but not PC. And then windows only had slooow drivers for the colorful modes. Yeah, stupid office application paid the bills even in the 90s.

[@ShadowTenReal]

Well, you have used 30 years old software for explaining HAM mode. Try to use more modern converters like HAM_Convert JAVA written programm to see the true power of this mode.

[@vix_in_japan]

I have, it's rather good. I really like the dithering options and the flexibility of it, I guess I'll do a video on that too :) In fact the Tokyo night scene was done with HAM Convert. But it's nice to show the software of its time on the machine itself as well.

[@Tenraiden]

RANMA!

[@Archimedes75009]

It would have been more educational to explain what a base is, explaining why us humans use base 10, and why computers use base 2, and how each bit set represents a power.

[@vix_in_japan]

Yeah I get what you're saying, I was trying not to overload with information and keep the run time to a reasonable length although maybe mentioning that each bit is a power of 2 -- I'm an artist not a mathematician so perhaps that's why I overlooked saying that, but a fair point made :) But feel free to drop a comment on those topics and I'll pin it to the top of the comments here so others can find it helpful.

[@10MARC]

Above all it was a video about HAM mode and not mathematical theory, though.

[@Syklonus]

Not needed. The section on binary was enough for a solid and more importantly - understandable presentation. Anything more would have put people off, so it was a wise choice not to bloat the information.

[@ArneChristianRosenfeldt]

@@Syklonuswould not need to mention base if we could just please bytes for pixels like on SNES mode-7 or VGA.