Blogs

Land(scape) ahoy!

April 16, 2021 Retro Ports

Now up to the demo proper. The initial landscape is drawn (hard-coded routine, not part of the landscape data), the stage indicator on the head-up display is rendered, and things are about to start moving! As I suspected, the demo will comprise much of the remainder of the code, which …

Blogs

Waiting for the demo…

April 15, 2021 Retro Ports

┬áTranscoding is progressing nicely. The three attract mode screens (challenge, high scores and score table) are now complete, and the game cycles through to start the demo. The sequence and timing of events and colours and graphics all match what’s happening in MAME (graphics corruption aside). I’ve been …

Blogs

Somewhat attractive so far…

April 14, 2021 Retro Ports

┬áNot a lot of time so minimal progress, but something to show for it. So far the code has been straightforward to transcode. I think that’ll be the case for quite a while yet, as I work through the attract mode scripts and underlying functionality. I’m not quite …

Blogs

On a high!

April 13, 2021 Retro Ports

┬áVery quick update as it’s late… implementing the script processing and now it clears the rectangles and prints “HIGH SCORE” in attract mode. There’s a bit of jumping around in the code, but on closer inspection it can be unravelled into a single function… at least that’s how …

No Picture
Blogs

All sticking to the script (so far)…

April 12, 2021 Retro Ports

Transcode is progressing well. I’m starting to get a better feel for the structure of the game. So far I haven’t had to do any gymnastics to mimic the Z80 ASM code execution flow in C – but early days yet. I’ve added an NMI (60Hz) and started on the …

Blogs

The first thing I C!

April 11, 2021 Retro Ports

I got a few minutes to start on the transcode today. I did a very, very preliminary scan of the code to get an idea of the data and code structures and its suitability to be converted to C a few days ago; now I’m simply working through the execution …

No Picture
Blogs

The first thing I C!

April 11, 2021 Retro Ports

I got a few minutes to start on the transcode today. I did a very, very preliminary scan of the code to get an idea of the data and code structures and its suitability to be converted to C a few days ago; now I’m simply working through the execution …

Blogs

Looking like a dump!

April 9, 2021 Retro Ports

I’ve now got the Scramble code reading a memory dump from MAME and rendering the tiles and sprites to faithfully recreate the display, with the correct colours. The tiles and sprites are blitted from bitmap sheets in memory, so a single call to Allegro is all that is required. It’s …

Blogs

Has got to be seen to be believed!

April 8, 2021 Retro Ports

Years ago I wrote some C/Allegro code to rip the Galaxian graphics for my FPGA implementation. It displayed the graphics so I knew the format was correct, and output some VHDL source code for the palette logic and graphics ROM contents (pre-rotated for a horizontal display). Today I took that …

Blogs

Scrambled Priorities

April 6, 2021 Retro Ports

I know I should be finishing off projects but I just can’t get into them right now. I need something new to pique my interest before I return to that stuff. So for now, I’ve decided to look at Scott Tunstell’s Scramble source code and see if I can transcode …