We asked both people involved in making this great demo how everything took place. Text by Ghandy of Nukleus.
Older gamers will surely still remember the most popular flight simulator of all time, the 1988 Intellisoft (EA) release, “F/A-18 Interceptor“. For the gamers the real challenge was landing on the aircraft carrier after completing the mission. The real-time graphics were impressive by the standards of the late 80s. I bet, at the time, almost every Amiga owner had a copy of this game.
This may also explain why the creators of the ‘Interceptor Intro‘ by Complex and Zymosis recreated the flight of the fighter jet in their own production, without assistance from the Amiga’s CPU. It came eleventh in the Amiga demo competition at Revision 2025. But a lot of other impressive productions were released to compete with their single-effect demo at that time. So the ranking came as no surprise.
Even though it’s not new anymore, we wanted to ask the creators a few questions to find out more about this no CPU demonstration for ECS Amigas.
The two creators introduce themselves
Could you please first introduce yourselves (Saviour and Dr Robotnik) to our readers?
Hello Lars, we are:
Saviour of Complex & Zymosis, 53 years, divorced with one son. I started sceneing in our small group NFL (nice fu*king life) with a couple of demos that are a bit lost now, moved to form an Amiga section at a C64 group Pu-239 after that and ended up in Complex a year later. Also been with Zymosis for a long time.
Most of my releases are at Demozoo. I was also the main coder of the game Elfmania.
Helo, I’m Dr. Robotnik, previously Silvery, sometimes Robottitohtori, a 47 years young gardener, music entusiast, drummer, producer and an avid mushroom forager. “Married” but not marrried.
I released a bunch of modules back in the 90’s as Silvery, but then gravitated more towards vinyl and cd releases and live performances both as a solo artist (Dr. Robotnik) and with various bands and projects (Usva, Coach & Toverit, MC Timo & Syntikka-Janne, Profeetta, Disorder of Deadeight, etc). I also coded a dentro a few years back!
“Somehow Interceptor came to my mind…“
The original Intellisoft game ‘F/A-18 Interceptor’ displays real-time polygonal 3D graphics. Why did you decide to use their cockpit graphics for your demo? What was your motivation to do so? Was it a hard task to do so?
Originally I just wanted to do some cool color effects with today’s advanced functions, next I added the tilting of horizon with copper color stripes as it suited the coding with copper and blitter paradigm. Somehow Interceptor came to my mind and wanted to add the cockpit and moving ground to make it more dynamic and about flying. Actually finding a proper cockpit graphics did take a few attempts, many of the screenshots I found were somewhat off pixel or colorwise, also reduced the colors to 16 as there were 20 or so colors in use.
You did it in a completely different direction and used only the copper and blitter. Why did you choose to take on the challenge of not using any CPU? What is the story behind this effect, and how did you come up with the idea? Please explain it to us non coders, thanks! You even used your own mod player, abusing the copper/blitter. Please explain, how was this possible?
“blittercpu” routines were first made for demo purposes, analogous to CPU instructions like ADD,SUB,CMP,BEQ,BNE so I could make more advanced effects with the nocpu approach. A decent mod player was made possible with the help of those and I took leonard’s light speed player as a base for the module format, making my own converter and adding a few things to make it playable using this approach. The whole mod player is only about 50 lines of code using the functions mentioned above. It does consist of 27 blits though.
ADD is the most advanced function of those, a single blit accessing a single word multiple times and doing the carry bit operation that is needed for add operation, doing what a CPU loop of 16 iterations would do. Afterwards it turned out that blueberry had come up with the exact same solution on paper except he had also figured out that the initial clearing of intermediate result is not actually needed as the carry bit operation does that anyway.
Copper showdown was brought to my attention late 2024 and it was what I was looking for, coding amiga with instant feedback as in 8bitworkshop.com for the c64 that got me into c64 coding. Also I always thought blitter was kind of my forte from the time with amiga demos in the early 90s. The magnetic field effect in Delirium in particular where a new effect using the blitter was invented, people still ask me how it is done.
It would have been possible to include the cracktro as well.
It would have been great to see a crack intro before the free flight started. I’m especially thinking of the legendary Unit A intro. But I guess that wouldn’t have been possible by using only the copper/blitter, or? 😉 No, of course not. Anyway, here are some background informations about the flaming war being spread in the cracktro.
Actually the intro would be not so difficult to implement in pure copper/blitter using the blittercpu and mod player functions…
The whole story of this group is really interesting. Or maybe I just remember that cracktro from the early ’90s in my living room because the whole game was really fascinating, at least for me. I used to read the scroll text from Unit A over and over again back then more than 30 years ago. I can’t speak for how you felt about it, but I consider the crack intro, when it appears in combination with the game, to be an integral part of the artwork as a whole. What do you think?
Loved Interceptor the game also, had the same cracked version and think the intro was a nice touch aswell. Suits the game well.
In the original game, the composer David Warhol used music based on the film ‘Top Gun’. Was that too military or maybe too commercial for you? Or did you just want to do something of your own?
We were taking ST-01 samples and electric guitar on the amiga with Dr.Robotnik and I happened to request an amiga mod from him that uses electic guitar samples.
A few more demos are already finished and in the making
Are there any plans for further productions using your new coding technology?
There is another demo already been made with the same approach, it would have been released at a party two weeks ago but the organizers had some kind of hickup running it. It’s the same Amiga OCS 512/512 format as interceptor intro though. Hoping to release it at skrolli or mysdata as soon as possible. It’s not as “serious” as interceptor intro but made with the same copper/blitter approach and the mod player. Ozzy Demo was released at Skrolli party.
“Interceptor Intro” was not expected to be a party winner
Apparently, many people did not understand how your demo came about. Were you disappointed with your ranking in the Revision competition? Or did you not care, as your main focus was to demonstrate the possibility?
Yes, it was mainly just to show the possibility of doing a demo using only the copper and blitter and to show off the mod player. It was never expected to be a party winner as it’s not the greatest Amiga demo as such and there were so many great demos in the compo. Nevertheless it was exciting to see it in the compo especially after not having released a demo in 33 years!
As I was finalizing the demo everything worked perfectly until I tried it on the real hardware a few hours before Revision deadline, I had to move the screen 16 pixels right but then I got some weird 2 pixels wide copper delay that resulted in sky being visible beyond the cockpit graphics on the right. So I had to add a two pixel wide whole screen high black sprite covering the extra pixels. Luckily there was one sprite left to implement the kludge.
Guys, thanks for this production and of course for your replies.
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