Rensoup: The goal is to make the best game for Atari computers

December 11, 2020 • Updated: Mar 17, 2025 - 11:39 PM

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Rensoup is the name behind what promises to be the best port of “Prince of Persia” – the classic platform game from Brøderbund Software (1989) – for all 8-bit computers. Some time ago, Rensoup gave this interview to Atariteca about his project – which he is developing together with the talented Konstantinos “TIX” Giamalidis (Greece).

Tell us a little about yourself and how you got into computing: what was your first computer and what prompted you to start programming/developing for it?

Rensoup: Actually, my first computer was an Atari 600XL with the tape recorder. I wanted to make games, of course, but I really had no idea. I started with a few (designing the graphics on paper) but they always ended up in the trash. I remember trying to make a Pac-Man clone, where the ghosts got stuck as soon as they had to choose a path… My best achievement was probably a Ghostbusters picture drawn in F mode with horizontal sequences of PLOT and DRAWTO. It took me 15 minutes to draw, but it was mind-blowing, much better than the one in the Activision game… Sadly, I lost it.

How did your relationship with Atari 8-bit computers begin?

I think I bought a 600XL because there were a lot of stores selling it. It was marketed as a serious machine, with serious software; so that was enough to convince my dad to get one so he could use it for word processing… Of course he never did.

I also got the tape recorder; and eventually also the 64KB expansion, the 1050 disk drive, the graphics tablet and a colour monitor (I started with the family black and white TV). I also got a strange GE printer, which was not very compatible with the A8. Let's be honest, I mostly played games and did some stuff in BASIC.

Do you still have an Atari 8-bit computer? What model or hardware do you have?

No, I sold it a long time ago and bought an AtariST… I'd like to buy one of those mini XL/XE machines, but they seem to be outrageously expensive.

How do you remember the Atari scene when you were just a computer user?

Around here, it was just me and a buddy. I had the Donkey Kong cartridge and he had Qix, so we traded them. Eventually, we both got the 1050 disk drive and started answering ads in newspapers, where people were selling cracked software at inflated prices.

What are your favorite Atari 8-bit games of all time? Why?

There were quite a few, although it didn't seem like it back then with so many low quality releases flooding the platform. As I said, Donkey Kong was the first game I owned and it was a great conversion.

I really liked the non-scrolling action-adventure games, which had the perfect mix of dexterity, puzzle-solving, and good design too. These include Conan, Bruce Lee, Zorro, The Goonies.

Karateka for its great fighting and lush animations. Whistler’s Brother, Gumball, Boulder Dash for their innovative concepts and good execution.

In the shooter section, Gyruss: good concept, good music; Dropzone: impressive effects; Last Star Fighter; Attack of the Mutant Camels; Stealth and Encounter.

International Karate, Spelunker, Spy vs Spy, Ballblazer, Donkey Kong Jr, Pitfall 2, Dig Dug, Mr. Do, Joust, Lode Runner Rescue, Fort Apocalypse, Montezuma’s Revenge… they weren’t that special but they deserve a mention.

I wasn't that big a fan of The Eidolon, Rescue on Fractalus! or Koronis Rift which are generally popular.

Any that you “admire” for its technical aspects or any other in particular?

I didn't really understand the technical side of games back then, but I was impressed by Karateka's animations and generally enjoyed great graphics in most of the games I mentioned before.

The Lucasfilms games were pretty visually impressive but a bit boring.

Which of your projects do you like the most? Why?

Prince of Persia (PoP) is the only project I've done on the A8, but I'm pretty happy with the result (it's not completely finished at the moment). I wanted it to be a great looking conversion, so I set some goals that I guess a lot of people didn't think were achievable, but you never know if something is good until you try it.

How did the idea of making the Prince of Persia port come about?

I saw MrSid's C64 conversion and then Bitshifters' BBC Micro port. They kept diaries and I was hooked. PoP has that mythical aura and it's a great challenge.

I checked to see if the Atari 8-bit version existed; and apart from long discussions on the AtariAge forums and very, very early concepts, there was nothing. So I started and stayed quiet until I had the first working version in November 2019.

The goal was to create the best 8-bit PoP port (while respecting the original specifications) and who knows… the best looking game for the A8… or maybe just the best game for the Atari 8-bit!

I wasn't really interested in the original art; I saw a bunch of graphics reworked by TIX for other games on the Atari Age and contacted him. He agreed without knowing the project. I then revealed to him that I was PoP, and he told me to go to hell! So that was a pretty short collaboration... but I persisted and he eventually gave in. Here's more or less how it happened.

What is the most difficult or challenging feature in PoP development?

Porting the game wasn't that difficult because I did it in incremental steps. I started with the fully functional BBC version and made an emulated PC port. Basically a 6502 emulator with all hardware access redirected to the PC code (graphics, sound, disk, input). I think this is how the AtariST and Amiga versions were ported as well.

Once I had it working, I "simply" replaced the PC code with the Atari code; and that's basically the November 2019 release, in 4 colors. I could have polished it up a bit and it would have been a proper port.

Going further was the challenge: I wanted additional colors on the characters and that caused all sorts of problems. First, I didn't have memory for those extra colors. Then, I had to constantly optimize the space, which was a really big job. Then I had to optimize the speed because the game was getting slower.

Then the actual work on a system to get more colors on the characters… basically “multiplexing” hardware sprites with a system to dynamically change DLIs. Using hardware sprites also meant that they wouldn’t properly mask with backgrounds; so I had to come up with a hack to get around that as well.

Another minor challenge was optimizing the speed whenever the game has moving background objects, because that caused unpleasant slowdowns that affected gameplay.

Tell us about the video…

This was the initial development environment used for PoP. Basically a PC port of the game using my own 6502 emulator, very limited emulation of the BBC's disk/memory input and accesses. DirectX was used for graphics. The art is from the original Apple2 version.

The large window with red and green blocks is the 64 KB memory space, where each square represents a byte: red means the byte was written; green, it was both written and read.

The orange area is the A8 hardware register space (which I didn't use at the time, because I hadn't started the conversion yet). And the small white boxes are the addresses where a tag is defined in the source code. By hovering over the area, you can get the name of each tag.

Blocks are updated in real time as the game runs, which is interesting to see what is being updated. It was useful for keeping track of unused space.

I understand that in the process you got in touch with Franco Catrín (Chile), who started a similar project years ago. Could you tell us about it?

Yes, Franco had a sprite routine that was less memory intensive, but a bit slower, so I asked him if he could modify it to work with screen clipping and optimize it as well. It started to do some things, but then it disappeared.

It's a free software project, so I don't expect people to keep their promises (well, nothing was actually promised). In the end I kept my bloat sprite routine and optimized it a lot more!

How do you rate the participation of members of the Atari Age forums?

It's mostly good… A lot of people are positive about Prince of Persia. And there's a fair amount of knowledge sharing. At one point I was looking into sound playback; and member Dmsc stepped up and actually wrote a great sound player!

For the development stage, Phaeron's Altirra emulator is pretty good. It would certainly have been a lot harder to develop PoP without it. Plus, you can post feature requests on AtariAge. Of course, there will always be people who will criticize you no matter what you do.

What are your plans for Atari computers in the near future?

I don't know... PoP is taking much longer than I wanted. I do have some kind of deal with TIX though, but maybe he's forgotten!

What is the main lesson you have learned during this time you have dedicated to the Atari 8-bits?

Nothing is free when you're dealing with a 1.79Mhz computer… especially when the CPU is a 6502 which is terribly inefficient. Five sprites just aren't enough. Especially when most of the circuits seem to be there for 8.