Hitting the Books: Amiga and the birth of 256-color gaming

With fashionable consoles providing avid gamers graphics so photorealistic that they blur the road between CGI and actuality, it is simple overlook simply how cartoonishly blocky they have been within the 8-bit period. In his new ebook, Creating Q*Bert and Different Traditional Arcade Video games, legendary recreation designer and programmer Warren Davis remembers his halcyon days imagining and designing a few of the largest hits to ever grace an arcade. Within the excerpt under, Davis explains how the trade made its technological leap from 8- to 12-bit graphics.       

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Again at my common day job, I turned notably fascinated with a brand new product that got here out for the Amiga pc: a video digitizer made by an organization referred to as A-Squared. Let’s unpack all that slowly.

The Amiga was a not too long ago launched dwelling pc able to unprecedented graphics and sound: 4,096 colours! Eight-bit stereo sound! There have been picture manipulation applications for it that would do issues no different pc, together with the IBM PC, may do. We had one at Williams not solely due to its capabilities, but additionally as a result of our personal Jack Haeger, an immensely gifted artist who’d labored on Sinistar at Williams a couple of years earlier, was additionally the artwork director for the Amiga design group.

Video digitization is the method of grabbing a video picture from some video supply, like a digicam or a videotape, and changing it into pixel information that a pc system (or online game) may use. A full-color {photograph} may include thousands and thousands of colours, many simply subtly totally different from each other. Regardless that the Amiga may solely show 4,096 colours, that was sufficient to see a picture on its monitor that seemed virtually completely photographic.

Our online game system nonetheless may solely show 16 colours complete. At that degree, photographic pictures have been simply not attainable. However we (and by that I imply everybody working within the online game trade) knew that will change. As reminiscence turned cheaper and processors quicker, we knew that 256-color techniques would quickly be attainable. Actually, once I began wanting into digitized video, our {hardware} designer, Mark Loffredo, was already taking part in round with concepts for a brand new 256-color {hardware} system.

Let’s discuss colour decision for a second. Come on, you understand you need to. No worries should you don’t, although, you’ll be able to skip these subsequent few paragraphs should you like. Shade decision is the variety of colours a pc system is able to displaying. And it’s all tied in to reminiscence. For instance, our online game system may show 16 colours. However artists weren’t locked into 16 particular colours. The {hardware} used a “palette.” Artists may select from a reasonably big selection of colours, however solely 16 of them might be saved within the palette at any given time. These colours might be programmed to alter whereas a recreation was operating. Actually, altering colours in a palette dynamically allowed for a standard approach utilized in previous video video games referred to as “colour biking.”

For the {hardware} to know what colour to show at every pixel location, every pixel on the display needed to be recognized as a kind of 16 colours within the palette. The gathering of reminiscence that contained the colour values for each pixel on the display was referred to as “display reminiscence.” Numerically, it takes 4 bits (half a byte) to characterize 16 numbers (belief me on the maths right here), so if 4 bits = 1 pixel, then 1 byte of reminiscence may maintain 2 pixels. In contrast, should you needed to have the ability to show 256 colours, it will take 8 bits to characterize 256 numbers. That’s 1 byte (or 8 bits) per pixel.

So that you’d want twice as a lot display reminiscence to show 256 colours as you’d to show 16. Reminiscence wasn’t low-cost, although, and recreation producers needed to maintain prices down as a lot as attainable. So reminiscence costs needed to drop earlier than administration authorised doubling the display reminiscence.

At this time we take without any consideration colour resolutions of 24 bits per pixel (which doubtlessly permits as much as 16,777,216 colours and true photographic high quality). However again then, 256 colours appeared like such a luxurious. Regardless that it didn’t method the 4,096 colours of the Amiga, I used to be satisfied that such a system may lead to near photo-realistic pictures. And the thought of getting movie-quality pictures in a online game was very thrilling to me, so I pitched to administration some great benefits of getting a head begin on this expertise. They agreed and acquired the digitizer for me to mess around with.

The Amiga’s digitizer was crude. Very crude. It got here with a bit of {hardware} that plugged into the Amiga on one finish, and to the video output of a black-and-white surveillance digicam (offered individually) on the opposite. The digicam wanted to be mounted on a tripod so it didn’t transfer. You pointed it at one thing (that additionally couldn’t transfer), and put a colour wheel between the digicam and the topic. The colour wheel was a round piece of plastic divided into quarters with totally different tints: purple, inexperienced, blue, and clear.

While you began the digitizing course of, a motor turned the colour wheel very slowly, and in about thirty to forty seconds you had a full-color digitized picture of your topic. “Full-color” on the Amiga meant 4 bits of purple, inexperienced, and blue—or 12-bit colour, leading to a complete of 4,096 colours attainable.

It’s onerous to consider simply how thrilling this was! At the moment, it was like one thing from science fiction. And the coolness of it wasn’t a lot the way it labored (as a result of it was fairly rattling clunky) however the potential that was there. The Amiga digitizer wasn’t sensible—the digicam and topic wanted to be nonetheless for therefore lengthy, and the time it took to seize every picture made the method mind-numbingly sluggish—however simply being able to provide 12-bit pictures in any respect enabled me to start out exploring algorithms for colour discount.

Shade discount is the method of taking a picture with quite a lot of colours (say, as much as the 16,777,216 attainable colours in a 24-bit picture) and discovering a smaller variety of colours (say, 256) to finest characterize that picture. For those who may do this, then these 256 colours would type a palette, and each pixel within the picture could be represented by a quantity—an “index” that pointed to one of many colours in that palette. As I discussed earlier, with a palette of 256 colours, every index may match right into a single byte.

However I wanted an algorithm to determine how you can decide the most effective 256 colours out of the 1000’s that may be current in a digitized picture. Since there was no web again then, I went to libraries and started combing via tutorial journals and technical magazines, trying to find analysis achieved on this space. Ultimately, I discovered some! There have been quite a few papers written on the topic, every outlining a special method, some simpler to grasp than others. Over the subsequent few weeks, I carried out a couple of of those algorithms for producing 256 colour palettes utilizing take a look at pictures from the Amiga digitizer. Some gave higher outcomes than others. Photos that have been inherently monochromatic seemed the most effective, since most of the 256 colours might be allotted to totally different shades of a single colour.

Throughout this time, Loffredo was busy growing his 256-color {hardware}. His plan was to help a number of circuit boards, which might be inserted into slots as wanted, very like a PC. A single board would provide you with one floor airplane to attract on. A second board gave you two planes, foreground and background, and so forth. With sufficient planes, and by having every airplane scroll horizontally at a barely totally different fee, you can give the phantasm of depth in a side-scrolling recreation.

All was transferring alongside easily till the day phrase got here down that Eugene Jarvis had accomplished his MBA and was returning to Williams to move up the video division. This was huge information! I believe most individuals have been fairly enthusiastic about this. I do know I used to be, as a result of regardless of our motion towards 256-color {hardware}, the video division was nonetheless with no robust chief on the helm. Eugene, given his already legendary standing at Williams, was the proper individual to take the lead, partly as a result of he had some robust concepts of the place to take the division, and in addition as a result of administration’s religion in him. Whereas anyone else must persuade administration to associate with an concept, Eugene just about had carte blanche of their eyes. As soon as he was again, he instructed administration what we would have liked to do they usually made certain he, and we, had the sources to do it.

This meant, nevertheless, that Loffredo’s planar {hardware} system was toast. Eugene had his personal concepts, and everybody shortly jumped on board. He needed to create a 256-color system primarily based on a brand new CPU chip from Texas Devices, the 34010 GSP (Graphics System Processor). The 34010 was revolutionary in that it included graphics-related options inside its core. Usually, CPUs would don’t have any direct connection to the graphics portion of the {hardware}, although there may be some co-processor to deal with graphics chores (similar to Williams’ proprietary VLSI blitter). However the 34010 had that functionality on board, obviating the necessity for a graphics co-processor.

Trying on the 34010’s specs, nevertheless, revealed that the velocity of its graphics features, whereas well-suited for gentle graphics work similar to spreadsheets and phrase processors, was definitely not quick sufficient for pushing pixels the best way we would have liked. So Mark Loffredo went again to the drafting board to design a VLSI blitter chip for the brand new system.

Round this time, a brand new piece of {hardware} arrived within the market that signaled the subsequent technology of video digitizing. It was referred to as the Picture Seize Board (ICB), and it was developed by a gaggle inside AT&T referred to as the EPICenter (which ultimately cut up from AT&T and have become Truevision). The ICB was one in every of three boards supplied, the others being the VDA (Video Show Adapter, with no digitizing functionality) and the Targa (which got here in three totally different configurations: 8-bit, 16-bit, and 24-bit). The ICB got here with a bit of software program referred to as TIPS that allowed you to digitize pictures and do some minor modifying on them. All of those boards have been designed to plug in to an inner slot on a PC operating MS-DOS, the unique text-based working system for the IBM PC. (You could be questioning . . . the place was Home windows? Home windows 1.0 was launched in 1985, but it surely was terribly clunky and never broadly used or accepted. Home windows actually didn’t obtain any type of recognition till model 3.0, which arrived in 1990, a couple of years after the discharge of Truvision’s boards.)

Slightly little bit of trivia: the TGA file format that’s nonetheless round in the present day (although not as common because it as soon as was) was created by Truevision for the TARGA sequence of boards. The ICB was an enormous leap ahead from the Amiga digitizer in that you can use a colour video digicam (no extra black-and-white digicam or colour wheel), and the time to seize a body was drastically diminished—not fairly instantaneous, as I recall, however solely a second or two, reasonably than thirty or forty seconds. And it internally saved colours as 16-bits, reasonably than 12 just like the Amiga. This meant 5 bits every of purple, inexperienced, and blue—the identical that our recreation {hardware} used—leading to a true-color picture of as much as 32,768 colours, reasonably than 4,096. Palette discount would nonetheless be an important step within the course of. The best factor in regards to the Truevision boards was they got here with a Software program Improvement Package (SDK), which meant I may write my very own software program to regulate the board, tailoring it to my particular wants. This was actually wonderful! As soon as once more, I used to be so excited in regards to the prospects that my head was spinning.

I believe it’s protected to say that most individuals making video video games in these days thought in regards to the future. We realized that the velocity and reminiscence limitations we have been pressured to work beneath have been a short lived constraint. We realized that whether or not the online game trade was a fad or not, we have been on the forefront of a brand new type of storytelling. Possibly this was a little bit extra true for me due to my curiosity in filmmaking, or possibly not. However my experiences to date within the recreation trade fueled my creativeness about what may come. And for me, the holy grail was interactive motion pictures. The notion of telling a narrative during which the participant was not a passive viewer however an energetic participant was extraordinarily compelling. Folks have been already experimenting with it beneath the constraints of present expertise. Zork and the remainder of Infocom’s textual content journey video games have been in all probability the earliest examples, and extra would comply with with each enchancment in expertise. However what I didn’t know was if the expertise wanted to realize my finish aim—absolutely interactive motion pictures with film-quality graphics—would ever be attainable in my lifetime. I didn’t dwell on these visions of the long run. They have been simply ideas in my head. But, whereas it’s good to dream, in some unspecified time in the future you’ve received to come back again all the way down to earth. For those who don’t take the one step in entrance of you, you could be certain you’ll by no means attain your final vacation spot, wherever that could be.

I dove into the duty and started studying the precise capabilities of the board, in addition to its limitations. With the primary iteration of my software program, which I dubbed WTARG (“W” for Williams, “TARG” for TARGA), you can seize a single picture from both a reside digicam or a videotape. I added a couple of totally different palette discount algorithms so you can attempt every and discover the most effective palette for that picture. Extra importantly, I added the power to search out the most effective palette for a gaggle of pictures, since all the photographs of an animation wanted to have a constant look. There was no chroma key performance in these early boards, so artists must erase the background manually. I added some instruments to assist them do this.

This was a far cry from what I finally hoped for, which was a system the place we may level a digicam at reside actors and immediately have an animation of their motion operating on our recreation {hardware}. Nevertheless it was a begin.