Why not use a tool if it’s available, right? I’ve been experimenting with ChatGPT for a while and it writes generally abysmal Assembly code for the C64. That’s probably because its training data on this specific language is tiny. Now I would really like to have a generator that does all of the boring stuff discussed in the previous post. Writing reams of repetitive code to parse out individual words is not my idea of fun, but it’s a necessary evil to get this game working. So I recruited the machine to do the machine’s job!

Following up on yesterday’s conceptual musings, here’s some more meat to the actual implementation. In this blog I’m exploring the actual Assembly code that converts individual words to tokens for use by the input parser later on in the process.

Leisure Suit Larry originally featured a free text input system that allows the player to enter instructions for Larry to carry out. These instructions take the form of sentences in plain everyday English. Parsing and interpreting this so that a video game can make sense of it is quite a challenge. Can we teach a computer English? It seems so, but not one from the 1980’s. The Commodore 64 does not have the RAM nor does it have the CPU to completely parse English setence structures and grammar. But the good news is: neither did the PC on which Larry first came out. There are tricks involved!

As mentioned earlier, I’m not porting AGI but writing Larry again from scratch to cater to the specific strengths and weaknesses of the C64 as a platform. I’m doing this in 6502 Assembler as that’s the only way for me to gain the required speed and control over the hardware that is needed to pull all the tricks I need. In this post I’ll provide more detail on how the screen actually gets drawn.

To borrow the words of the greatest hero of all time who never was, Samwise Gamgee: I’m back! And it’s been quite a ride this past month. Let’s stick with the project and surrounding computer stuff for now.

Nobody knows why exactly, but my cartridge code is now alive. The problem is on the C64 side of things and mainly has to do with the routine that would copy my bootloader into a safe RAM location.

Started a new Git project for Larry on cartridge. Adapted the framework I found online and things now work. I can actually load a cartridge reliably and get the machine into a state that I can work with. Decided to do an intro sequence for the game. It helps that this forces me to deal with bitmapped graphics again, which is something I hadn’t incorporated into the automated build before.

Started a new Git project for Larry on cartridge. Adapted the framework I found online and things now work. I can actually load a cartridge reliably and get the machine into a state that I can work with. Decided to do an intro sequence for the game. It helps that this forces me to deal with bitmapped graphics again, which is something I hadn’t incorporated into the automated build before.

Had a few days off this project. Obviously that doesn’t mean that no on-topic thinking takes place, and it’s been fruitful. The Easyflash generator works correctly now as far as I can tell. Not releasing it to the world just yet, but for now I can generate a working EasyFlash cartridge.

Spending a little bit of time today on my EasyFlash generator. Decided to feed the tool YAML files instead of command line parameters. Defined the YAML spec in the README that goes with the tool.