Releasing Level One (C64)

We’ve reached the end game for 2018’s Intro Creation Competition so there’s been an inrush of new releases over the last couple of days including one last contribution from yours truly with the ever patient Andy Vaisey on music. It went through a few names but Level One was the final choice simply because it looks somewhat like a game.

The scrolling area takes up the entire regular screen – 39 visible characters across by 25 down – and is being moved using a double buffered scroll routine similar to the ones employed by games which in turn leans on some Run-Length Encoded background data. It also uses the C64’s Extended Colour Mode so, although there are only 64 characters available in the font, it can have four possible background colours for each character so I don’t have to scroll the colour RAM.

Something a little trickier is happening in the black bands above and below the scrolling; these are ten pixels high and sat in the borders, but containing a seven character wide Cosine logo and nineteen characters of either static text or scrolling message. To get twenty six characters into that space the code has to abuse the ghostbyte, splitting it at five points on each scanline to produce the extra two characters (they’re at the far left and right of the screen on both lines) and mask off the raster bars for the areas between the sprites.

I suspect a few people will be asking themselves if a game with similar graphics would be possible and the answer is a sort-of-yes, although drawing decent backgrounds when restricted to just 64 characters is bloody tricky!

Workprint – January 2018

I’ve missed my first Friday “deadline” for 2008 2018, that’s a cracking start to the year… having a cold is my excuse and I’m sticking to it, although that might just be the mucus!

The aftermath of the “festive season” means that I didn’t have much of note to write about at the moment anyway, I’m still hacking away in the background at the Hex Files remix when I can find time and have been mulling over a game for C64CD which will no doubt prove to be just another cheap excuse to write a scrolling shoot ’em up, but I’m tempted to throw some of the sillier ideas I’ve had for “features” into the mix for that one.

And before I forget, couple of folks have asked why Blok Copy or DYCP 2018 didn’t appear in last month’s workprint; that’s a simple one really, neither project had been decided upon when the post went live! I like to think of myself as spontaneous, although everyone else seems to feel it’s more “annoyingly erratic”.

DYCP 2018 (A8)

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.