I lost my heart to Agnus, Denise & Paula

c: | f: Technology / Software

What has 16-bits, exuded cool and made PC owners cry? Why, the Amiga of course. After tiring of BASIC on the Vic20 and typing strings of hex from the back of magazines into the Spectrum, the Amiga was my new main squeeze.

Back in the late 80s/early 90s, every cool cat either had an Atari ST or an Amiga. We blagged an ST for music at school by writing to the local council asking for funding, whereby we then convinced the music teacher to buy a Yamaha SY-22 synth, an Atari ST and a copy of Cubase 24. That sparked various bands, my frustration with the Atari as a music platform, and subsequent desire to own an Amiga, which led to home music and a record contract by the time I was 19.

What cemented my thirst for Commodore’s state-of-the-art technological wonder machine were quite simply the demos. I’d seen a few round a friend’s house and was slack-jawed with awe. I begged and hinted and begged again, and my parents eventually caved in.

Back when the Internet was primarily only JANET — the playground for university students — my Amiga-owning friends and I would scour the backs of magazines and dial-up bulletin boards to order the latest and greatest demos from the burgeoning graphics scene. Most of the demo writers were enthusiasts, hackers and crackers showing off what they could do with the Amiga’s architecture. Each month it seemed, things got better, faster, and more amazing as people learned how to bend the system to do things far beyond its intended capabilities.

The chipset of dreams

The astounding part about the machine — and forgive me as I delve into misty-eyed techno-geekery here for a moment — was its unique approach to parallel processing and true, pre-emptive multi-tasking. See, the humble PCs of the day had a CPU: the good ol’ 286, 386, and 486 chips with their arcane addressing system. But once the CPU was maxed out you had nowhere to go.

The Amiga had a CPU, of course; Motorola’s glorious 68000 upon which I learned to program in assembly language. But it also had a series of companion processors that allowed you to dial the fun up to 11, and beyond. There was Agnus for accessing chip RAM, Denise for moving sprites around the screen, and Paula for four-channel stereo sound (doubled to eight using the OctaMED tracker upon which we composed the demo track that led to our first commercial single).

These support chips enabled a staggering level of ingenuity to be applied to programming. Agnus in particular was the hottest gal for graphics because of her two sub-components: Copper and Blitter. With these two hotties alone you could manipulate the display in very complex ways with an incredibly simple instruction set (the Copper had just three instructions) because the chip timing was linked to the screen’s raster beam as it scanned across the display, line by line, fifty times a second.

You didn’t need bitmap graphics to draw a chequerboard, for example. Instead, you told the hardware to blit a square straight to video RAM and then copy it in a couple of instruction cycles. Agnus did the rest while the CPU hardly got involved. To animate it, you just programmed the Copper’s state machine to shunt pixels around when the video beam hit certain spots on the screen, again with the processor hardly noticing. You could then use a tracker to compose and overlay four-channel sound in under 3% CPU utilization thanks to Paula’s DMA trickery, and still have well over 90% of the system resources free for anything else you fancied.

Stuffing the result on an 880KB floppy disk meant you had a demo to make PC owners green with envy as they sat typing into their stilted Lotus 123 spreadsheets. For an early demonstration of using the Copper, check out Angels’ Copper Master demo. No sprites, no bitmaps, just colour manipulation and maths.

All this multi-processor goodness added up to mesmerizing displays of awesome for the time. The Amiga architecture was — and still is to some degree — far ahead of its time, and the rise of the PC took things a big step back in my opinion, until high-end GPUs caught on (but with a comparable price tag to consumers).

Early 90s demo wars

Before waxing lyrical about the demos themselves, one more little set of facts need bearing in mind:

  • The 68000 processor in the Amiga was clocked at 7MHz. Yes, just seven megahertz. If you’re reading this on a desktop or laptop there’s a good chance your CPU is clocked at between two and four GHz (yes, gigahertz) and your processor may have two or more separate cores.
  • The Amiga 500 had 512KB of RAM (with an expansion slot for a further 512, which mine had populated). One lousy megabyte. That’s less than a PC floppy disk can contain. Your phone probably has a four gigabyte card in it, which is around 4000 times as much memory.
  • The primary mechanism for loading data into the machine was a floppy disk drive. As touched upon earlier, each disk held up to 880KB of data. Less than one megabyte.

And yet, even in the face of these technical barriers, demo makers squeezed phenomenal amounts onto the disks. Each group released demos in a never-ending game of one-upmanship and bad spelling. Increasing the number of pixels in starfields, increasing the number of bitplanes for a zooming message scroller, spinning cubes and shapes faster then the rivals, real-time moving lightsources on ray-traced graphics, lightning fast mandelbrot generation, and twisting shapes that shouldn’t be twisted just to say “I told you so, now go do better”.

This resulted in some entertaining wars between demo groups, some of which spilled over into the demos themselves, as can be seen in the intro to Kefrens Desert Dream when they were having a spat with Melon Dezign. If you skip the Desert Dream intro, which is pretty tedious, the real fun starts at about four minutes with a typically awful poem by people whom English is definitely not their native language! But some of the technical achievements in the remainder of the demo deserve praise, especially turning thousands of dots into a light-sourced polygon.

Things progressed rapidly. Long, drawn-out demos were replaced with snappier affairs and then demo group Spaceballs stole the show, kicking the whole spinning ball, dots, rasters, lines, shapes and bendy things demo kingdom in the face. Their first break-the-mould offering was the 2 Unlimited inspired State of the Art, which they squeezed onto a single Amiga floppy. But they smashed that out of the park with the insanely clever Nine fingers a year later. Just two floppy disks — less than two megabytes of heavily compressed code — went into that and, again, ran on a stock 7MHz A500 with 1MB of RAM. The amount of optimisation and ingenuity that went into that demo alone is truly unbelievable. A lot of today’s coders could benefit from the lessons learned when resources were tight. Seriously, what can you achieve today in 2MB that compares?

As the chipsets progressed and the Amiga 600 and 1200 were born, things moved on. Spaceballs did it again with the liquid-metal morphings of Dark Helmets to a thumping soundtrack. The high energy Ikadalawampu by Loonies is a tour de force of sound-to-light mastery. And stuff like Starstruck by The Black Lotus is simply incredible for such a humble machine.

And now…?

We have PCs. We have Macs. We (thankfully) have Linux. We still have games consoles. But do we have any mainstream computer hardware these days that attract gamers, hackers (in the true sense of the word) and enthusiasts alike, to break technical boundaries in the endless pursuit of fun “because we can”?


The closest we have is the Raspberry Pi project, which is a breath of fresh air in the sanitized phone/tablet/app marketplace. The current crop of hardware teaches nothing of the raw beauty of the electronics behind the scenes. It doesn’t excite people to do stuff better than anyone else. It’s all flat and samey. Sumptuous touch and swipe is useless when it goes wrong and few can figure out how to hack it back into a working state without shrugging and reaching for the power button.

I sincerely hope Raspberry Pi continues to gain traction and leads to a breed of awesome designers and software visionaries like Jay Miner, the father of the Amiga. The world is short on people who believe in their pursuit of enabling others to achieve creative expression and have the gumption to see it through. Such people are the true heroes of our generation, making altruistic technical leaps in the spirit of pure desire to achieve.

I salute Jay Miner and his team. They quit their day jobs, went out on a financial limb to see their dreams become reality, and it worked beautifully. Albeit in a beige case.

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