So Blok Copy on the Atari 8-bit wasn’t the only Cosine contribution to the New Years Disk 2018 because Cosine also churned out a little demo called DYCP 2018. And yes, I know that’s a terrible title but I was taking the Roy Walker approach to naming for this one and, after scratching my head for a few hours, nothing better presented itself!
The main reason for this one is that Andy Vaisey sent along a great cover of the loading music from Uridium 2 on the Amiga; he’d produced it whilst getting his head around the Atari 8-bit’s POKEY sound hardware but the tune was triple speed (so is called 150 times a second rather than just 50) and needed code around it which wouldn’t mind being interrupted from time to time if you’ll excuse the “pun”. I wasn’t thinking about that as I delved through my workfiles but realised that one of my five year old DYCP prototypes would work in that respect and spent a morning making the two work together.
Why is there a copy of the C64’s power up screen here…? That’s mostly because the DYCP routine has been written the “C64 way” using one character set and arranging everything in memory to make drawing the letters as fast and efficient as possible.
Another release so soon? MD201706 is merely a plotter with some cosmetic niceness, but the code is a little unusual; it needs a SuperCPU (which can be emulated in recent versions of VICE and, unless it’s lying, it should run on either PAL or NTSC) or the Turbo Chameleon set to 6MHz or faster in order to run. Its single buffered and can clear, update and draw four hundred points a frame courtesy of the expansion hardware. It isn’t fully using the capacity of either device, the current firmware of Chameleon with its speed set to “no limit” is slightly faster than the SuperCPU but I restricted myself to 6MHz in case that top speed changes downwards with future updates.
A few people are probably going to ask “why” and the simple answer is “because”, but I’d actually been prodding around my unrolled plotter which was used in MD201704 on the C128, using 2MHz mode in the borders and found myself wondering just what my Turbo Chameleon could do with it. Then Wolf 3D for the SuperCPU arrived and I decided to make my code run with both. As always, GitHub is the source for… erm, the source and questions can be passed on in the usual manner.
This is probably going to be the end of season two for the Monthly Demo series because I want to take a little break to work on games… and yes, I’m already braced for the influx of responses that’ll probably get, so will be running away before this post goes out!
Two releases for the price of one this time, although they’re built on the same block of scroller code. WannaCrypt for the C64 and Atari 8-bit is a teensy demo with a loose copy of the WannaCrypt decryption tool and a scrolling message which is, due to a discussion about simple encryption at the Atari Age forums, reversibly mangled using a couple of simple techniques. Here’s the C64 version which features an old but still golden tune composed by Marc “Skywave” Francois…
…and this is what it looks like on the Atari 8-bit with graphical help from José Pereira and accompanied by Miker on the POKEY. There are even vertical colour splits being used on this one!
The source code for both the C64 and Atari 8-bit versions are available at GitHub, although they don’t come with the painfully hacky BlitzMax tool which takes some text and creates a mashed up binary file.