Category: crpg

Since my last post I’ve been experimenting with using the Commodore 64’s multi-color character mode. This mode allows you to display 4 different colours in each 8×8 pixel character cell but with the loss of horizontal resolution. Each “pixel” in multi-color mode is effectively made up of 2 horizontal pixels – this sometimes leads to the slightly “chunky” look of some C64 graphics in games. 1 colour is the background, 2 colours are set universally for each character using registers and the other comes from the C64’s screen colour RAM (one colour per character cell on screen).

It’s possible to use a mixture of multi-color mode characters with standard high-res characters on a single screen. This is done by setting bit 3 of each character cell’s color memory – the value of this bit determines whether a character on the screen is in standard high-res mode or multi-color mode. The downside of this is that you have a more limited selection of colours. Colour values of 0-7 in the colour RAM will display a high res character, 8-15 a multi-color mode character. This means you can’t use colours 8-15 in your display other than as one of the 3 universal colours – so no light red, shades of gray, light green etc (colours on the right hand side below).

I’ve done a bit of experimentation with Pixcen and produced a few sample multi-color tiles but it took me a while to understand how the colour limitations work and I find the loss of horizontal resolution hard to work with, and I have little artistic skill to start with! I also need to work out what my graphics development process is. Pixcen seems to be a good enough utility but I think there may be other tools which might suit me better. Some form of C64 graphic, tile and map editor might be required.

So I have a real balancing act to consider, deciding on whether to use multi-color mode (losing resolution and colour choice) or just stick to using high-res characters but having the limitation of a single colour per cell. I’m aware that I could use one of the C64’s bitmap modes which provides the programmer with control of individual on-screen pixels with greater colour flexibility but from what I’ve read that will use a lot of memory (8K just for the bitmap data) and would potentially be slower than using characters. Let me know your thoughts.

Here’s the latest image from my Commodore 64 RPG. I’ve added some additional tiles (from Ultima IV) as placeholders and to give me something to work with whilst coding game functionality.

The Ultima IV tiles and C64 character set are temporary.

I now need to add some additional maps to the game with working entrances and exits, initially just a town and a dungeon. I need to give some serious thought to map sizes and how I want to manage the wilderness map. Games such as Ultima IV and V would load sections of their wilderness map into memory as required but I’m not sure my map needs to be as large. I’d also like to add some basic combat with those red monsters on the wilderness map and some basic interaction with some example town NPCs.

I’m urgently feeling the need for some map editing tools. Whilst I could create some windows tools for these I’m considering making the tools run on the C64 as there will be a number of similar coding routines. There’s no shortage of things to keep me busy with this project and so far I’ve not run into any serious problems – memory and floppy disk space do concern me though…