Arlasoft

Posting to keep updated.

Code for centipede here: https://github.com/1888games/Centipede-Fairchild

A few bug fixes and improvements: Added high score (calculated upon game over, too expensive to calculate/update during play) Delete ship, flea, scorpion and spider when dead or reached new wave Restore undamaged mushrooms when dead (that may have been covered by a flea etc), just don't play the sound Delete last life icon when game over Add a delay before allowing button press on game over Prevent flea being drawn 'off screen' when reached bottom and about to be deactivated because enough mushrooms in player area Scorpion will restore mushrooms on the very edge of the screen when it despawns On a real controller, twist/pull/push will all now trigger a bullet centipede_CF_101.bin

This was going to be my last Channel F game but if I find myself with a day with nothing better to do, I want to do a pixel-perfect port of Snake II on the Nokia 3310. However I'm really struggling to understand how the layout works. The screen resolution is 84 x 48 (so perfect for the Channel F) and in a supposed screenshot the actual playfield is 82 x 38. So you can fit 27 3x3 squares across, or 20 4x4 squares. But when you play the game and count the snake has 23 horizontal positions. So the only thing I can think of is that it usually moves 3 pixels but sometimes will move 4, and the graphic drawn changes depending on your X position. So perhaps not as straightforward a port as I initially thought....

As for the score not being visible, is the picture on the TV centred? There should be 3-4 pixels either side that aren't displaying anything important so that gives a width of 94-96 pixels, do I have to make it 92 to be safe?

Thanks very much, means a lot coming from one of the authorities on the Channel F! I'll put in a high score and take a look at those bugs, looks like they're mostly visual, unless there's an immediately obvious fix (I know some things are not clearing up after themselves) I can live with those. I've never even held a Channel F controller so I'll look into adding the extra controls so the user can choose what suits them, the idea of a 'twist' or 'pull' is pretty alien. The controller reminds me a bit of the game 'bop it'.

Thanks! That is intentional and follows the arcade version, in wave one you should get a 12-pod centipede. Then 11-pod and 1 lone head, 10-pod and 2 lone heads and so on, until just 12 heads. Then it goes the other way until you're back to a 12-pod centipede again. As for tutorials, I've been thinking of writing a book for a while, and one about the history and how to program the Channel F would appear to be as pointless and niche an endeavour as any!

I've been working on a port of Centipede for the last week or so, in between changing newborn nappies. It's ready for testing, the only things left to add/fix are: Flea should be two hits to kill and double its speed on first hit Delete fleas and scorpions from playfield when you die or complete a wave Sometimes centipede bodies are orphaned from a head A little tune when gaining an extra life Prevent score digits occasionally going above 9 Other than that the gameplay should be pretty close to the rules here: https://www.ign.com/articles/2003/10/17/arcade-smash-hits-general-faq-455360 Intentional differences due to laziness: Poisoned mushrooms give 10 points per hit instead of 5 When a centipede reaches the bottom of the screen, instead of heading back up the screen he will re-enter the screen at row 13. At this point there is also a chance a new head will spawn at the top of the screen, rather than a 100% chance of one spawning at the bottom Let me know if you come across anything else! centipede.bin

Here's a fixed version of Tents & Trees that should now go beyond level 20. tents_CF.bin

Yeah, when it moves onto the next column it just reads the previous value back in from port 4 and then moves the accumulator along one. So it looks like if you don't actually end up plotting that pixel it is then reading a joystick value back from port 4 instead. So what happens is the entire first row isn't drawn in the right place - I assume most of the time the pixels are not visible but if my sprite is near the corners of the screen some of them are. I saw this before on the very first blit operation after my game started if I used a 'clear' background, and that must have been because I had just pressed fire to begin.

Anyone come across a bug in the blit function when the background colour is set as clear ($FF) and the first pixel is clear? It seems that by skipping actually outputting the pixel, but having output the row and column to the ports, I occasionally get a phantom pixel appearing near the left edge of the screen when the first solid pixel is drawn. It also seems to be related to recent joystick activity - I draw my sprite regardless of whether it's moved, but the corruption only happens if I press a joystick direction, even if the sprite isn't moving and has already been successfully drawn the previous time around the game loop. EDIT: Simple fix! Save the column value after the outs 4 to R0, then instead of doing ins 4 just load back in from R0. I assume this hasn't come up before because port 4 is joystick 2 and that's what I've got my controls set up on....

Well...once you've made 2048 it's a short hop, skip and a jump to turn it into Threes. So.... https://arlagames.itch.io/3rees-for-fairchild-channel-f 3rees.bin

Just realised that was for the title screen, for the light blue screen use: li %11000011

li %00000000 lr 3, A pi clrscrn Full code here: https://github.com/1888games/2048_Fairchild

Haha sorry! Once you get the hang of assembly and the common patterns it's not too bad, it's just moving numbers from one place to another. Like anything with practice you get faster. 18 months ago I'd never have believed I'd write so much as Hello World in assembly, it all clicked watching the Youtube series Let's Make A C64 Game. I'm quite surprised I got a handle on the instruction set so quickly though, I'm no longer having to think how I'd do it on the C64 and convert line by line. It's definitely a fun machine to program for. I want to try an action game next, I had 12 3 x 3 centipede sprites moving across the screen yesterday but the flickering in the absence of any game logic was a little scary!

Wrote another quick game last night and this lunchtime, a port of 2048. Rom is attached. Now to attack the Tents & Trees bug! https://arlagames.itch.io/2048-for-fairchild-channel-f 2048_F8.bin

Thanks for trying it, so basically I need to make sure everything fits inside a 96 x 58 area in the middle? Not lucky enough to have a real machine yet but have got my eye out for one. Have you got some sort of flash cart for it? I'll have a go at tracking down that bug later!

I also saw that with the online one, can't really be sure if that's my fault or the emulator, I can only assume MESS is more accurate...?

New version here with minimum tents per level to try and help the difficulty curve, also fixed the scores which weren't falling fast enough. tents_v100.bin

No haven't had a chance yet. Did you download the rom again from my last post, if so you must have just got unlucky. I'll put in a lookup based on the grid size for a minimum number of tents that should be placed.

Haha yeah, I suppose I could make the level generator try again if it fails to place enough trees - at the moment it only tries again if it didn't place any.

Great, thanks for trying it out. The initial rom I put in that post had the procedural levels broken, I was bashing a counter register in the debounce code.

I re-wrote the input code I'd lazily copied from Veswiki, I'd forgotten to debounce the controllers separately. Should work now, it works on this online emulator: https://www.lexaloffle.com/bbs/?pid=71273 game.bin

That's exactly what it should have been doing, I've made a change and attached - when you get a chance please could you let me know if it works. game.bin

What keys have you got mapped? I saw on another emulator the cursor just skips all the way in the direction you press, but on MESS 0.231 it seems fine. This is on a VM in Parallels though so I'll try it on a Windows laptop.