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View topic - Arcade Game Designer - experience SMS / Z80 coder help needed

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  • Joined: 20 Jun 2018
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Arcade Game Designer - experience SMS / Z80 coder help needed
Post Posted: Wed Jun 20, 2018 10:56 am
Hi guys

I think I might have posted about this before but things have moved on a fair bit. Some of you may know of Jonathan Cauldwell's Arcade Game Designer for the ZX Spectrum. A huge number of homebrew games have been built on it, include a few by myself. I also code in Z80.

A new multi-platform version of AGD is currently in development, and allows coders to write games on multiple machines at the same time. The front end consists of editors for graphics and a common scripting language. The back end has a compiler and an engine which converts the scripts directly into machine language for the appropriate machine. Currently there are compilers for ZX Spectrum, Amstrad CPC and Acorn Atom, with more being planned.

Since the SMS is also Z80 based, it seems a logical step to consider a version for this machine. I wonder if anyone is interested in joining our group and putting the work in to build an SMS engine / compiler. A decent amount of the Amstrad / Spectrum code could be adapted, but there would still be quite a lot of work involved. However, it could result in dozens of new SMS games, as well as the ability for non Z80 coders to build more.

Hope to hear from you!
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  • Joined: 01 Feb 2014
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Post Posted: Wed Jun 20, 2018 12:11 pm
While the Master System shares the z80 with the Spectrum and the Amstrad, its whole video architecture is vastly different. Thus a port of the AGD would probably end up being close to a complete re-write from scratch.

I‘m not saying it‘s impossible, but people familiar enough with SMS hardware to be able to port it are probably busy with game projects of their own, so don‘t be disappointed if no one really jumps at it.
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Post Posted: Wed Jun 20, 2018 2:11 pm
Yes, I understand that, I'm not holding my breath, but perhaps someone might like the sound of it, we're working on a really great dev environment that allows you to switch between different machines and requirements. The Spectrum scene is really vibrant, and I think a lot of people would love to be able to write SMS games without the need for hardcore Z80.
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Post Posted: Wed Jun 20, 2018 3:11 pm
Will the engine be open source?
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  • Joined: 20 Jun 2018
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Post Posted: Wed Jun 20, 2018 5:57 pm
everything we do with our work is community oriented, it's not for profit, and if we work with a coder who wants to build an SMS engine, we would encourage them to be open source, yes.
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  • Joined: 25 Feb 2006
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Post Posted: Wed Jun 20, 2018 10:55 pm
That could be awesome, if it becomes true. :)

AFAIK, one of the greatest challenges to make the tool hardware-independant would have to be the memory architecture: the SMS does not have much RAM, but has plenty of ROM; this means that mutable stuff and constants would have to be separated into different memory regions.
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Post Posted: Thu Jun 21, 2018 6:04 am
yes, that is always the challenge when thinking about 8 bit consoles compared to computers. However, on the Spectrum, the main AGD game engine is quite small, most of the memory is taken up with assets (sprites, objects, tiles, screens), so I imagine they could be loaded in. Of course, you guys would know a lot more about that than me :) it would need a real SMS expert to make it work, but it would open the system up to a lot more people.
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Post Posted: Thu Jun 21, 2018 7:22 am
You'd need to make non portable games to make the best of each system. SMS is going to favour many small sprites, full screen scrolling, and colourful graphics. Speccy will want less scrolling, 1 bit graphics with attribute clash, and sprites limited only by total drawing time. Having said that, a generalised content tool could be very useful because tooling is a big part of the work. If it can operate just as a tilemap editor, for example, that could be useful.
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Post Posted: Thu Jun 21, 2018 10:10 am
I have done two arcade conversions for the Spectrum - Terrapins and Roust (arcade games Turtles and Joust). If you google 'ZX Spectrum Roust' or 'ZX Spectrum Terrapins' you can see them. Both would work fine on the SMS.

Of course scrolling is a big miss, but a lot more is possible with AGD than people think, especially as it allows assembly to be integrated. We're talking homebrew here, smaller games that people make for fun, tools that non-coders can use, and if it worked, a nice library for people to try out.
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  • Joined: 22 Apr 2018
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Post Posted: Fri Sep 14, 2018 3:55 pm
I'd love to see Roust and Terrapins on SMS! More generally I'm happy to see interest in new game development tools for old computers and consoles.

I actually think a lot of Spectrum games may be good porting candidates, provided their actually modifiable RAM needs aren't excessive.

There isn't enough VRAM to bitmap the whole screen, unless you drop to the Genesis/MD-incompatible "TMS" video modes which have a lot of attribute clash limitations similiar to ZX Spectrum. You can make those modes work on Game Gear too provided you set up the palette.

Some games pay the port-indirect price and use the VRAM for work RAM to overcome the tiny system RAM (which was even tinier on the earlier SG-1000!) This can allow "soft sprite" code to run, but it's quite slow compared to the hardware sprites.

Others use extra work RAM on the cartridge (e.g. Castle Excellent and Sega BASIC for SG-1000 ... JP-SMS.) The EverDrives and emulators both implement enough of the "Sega" memory mapper protocol that you can use this to get 16K RAM at 0x8000-0xBFFF, though it may force your ROM to bankswitch if it's >32K. Plus it's battery or flash-backed so you can save progress across power cycles.
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