New version of Space Invaders (was: BASIC Space Invaders)

[JohnH]

Thanks Tricky, that's a lot of fun, as usual for your games.

[mygrandmawheels]

Very good as usual, Tricky! Another great jump backwards!
This is the pure spirit of retrosoftware, the best coding skill to serve obstinate and contrary technology!
Space invaders wasn't my favorite game, to tell the true, but the feeling is the same when I was 9 spending Sunday morning in the parish hall playroom.
There was ping - pong, a table football, two flippers, a Space Invaders and a Frogger.
So you just have rebuilt this snapshot of my past.
Well, your frogger is a masterpiece, I still can't figure out how you could squeeze every hertz of a beeb such a way.

Such a strange, the golden age of the beeb is now.. the second decade of 21 century!

[tricky]

Thanks, space Invaders wasn't one of my favorites either, but it was my first, and always there.

The only two things that are really different now are emulators, allowing more advanced debugging and a better understanding of virtical rupture.

The only thing that i regret is that Gil and I never finished Jeltron back in the day.

It would have been amazing to have had games like the darkness of raven wood and castle defender back in the day.

[kieranhj]

The only two things that are really different now are emulators, allowing more advanced debugging and a better understanding of virtical rupture.

The only thing that i regret is that Gil and I never finished Jeltron back in the day.

It would have been amazing to have had games like the darkness of raven wood and castle defender back in the day.

We also have better content creation tools in the form of modern PC-based sprite editors or image converters and music trackers. And we can preprocess an "impossible" amount of data on a PC to crunch it down to 8-bit format, ala Bad Apple video or Julian's partial-palette encoder.

It is great to see new games still being made for the machine. I will get round to one eventually once I've finished scratching the demo itch. (Just takes so long with real life in the way. )

There is still time for you to finish (rewrite?!) Jeltron Tricky...

[jonb]

Looks pretty good, tricky!

Do I take it that it's no longer "BASIC" Space Invaders?

[tricky]

No longer BASIC, just basic now, but apart from screen memory access, it should be OS friendly.

[Arcadian]

This was very popular at Saturday's Wakefield RISC OS show - however there's a graphical glitch to report (see vid):



Disabling the MMC rom on sydney's Model B fixed the problem. My BBC Master with internal datacentre ran the game from RAMFS no problem, however my other Master with external datacentre did display the glitching when run from RAMFS. Let me know if there's any more testing I can do to help diagnose!

[tricky]

I'll have a look later today, sorry, as i said it hadn't had much treating.

[sydney]

It was my master not a model b Dave.

[tricky]

Dave, that video doesn't seem to work, but I'll try some different configs.

[Arcadian]

Oops it was set to private. Now fixed.

[tricky]

That's not very good
I did make a last minute change to add the loading screen, it looks like the cleared bit is where it changes to mode 5 before changing to 256x256 mode 1.
My guess is that my CLS code isn't working, but I'm not sure why. I would guess a quick fix might be to add a mode 1 before the mode 7 in !BOOT.

[kieranhj]

Hey Tricky - finally had chance to try this today - looks really nice, super smooth update and accurate graphics, as always. Great work!

[tricky]

Thanks.

Here is an "official" fix for not clearing the screen at the start of the game, the MODE 1 before MODE 7 in !BOOT should also work fine.

Code: Select all

.MAIN
	
	lda #0 : tay
.clear_screen
	sta screen,y : iny : bne clear_screen
	inc clear_screen+sm_hi : bpl clear_screen

It could just clear &3000..&57FF as the mode 5 will clear the rest, but this is less code

[derek]

Hi,

Just downloaded this great game, tried on BeebDroid v1.3 on a Samsung SM-T530 works really well.

[tricky]

Glad to hear that, most of my games don't work very well with beebdroid, as they either hit the SBC bug or drive the 6845 in a way that beebdroid doesn't understand.

[tricky]

I've got a new capture setup so thought I would post Space Invaders on a real beeb with commentary.

https://youtu.be/Zaj6xo3lpkA best watched in 720p on a 50Hz monitor.

[tricky]

I don't know if I ever posted the version with sampled sound, so here it is (again?).

[TobyLobster]

These sounds are great, they really help sell the arcade-ness of it.

[tricky]

Here is a small tweak to Space Invaders, this one lets you use user defined graphics for the invaders on the top row.
The !BOOT looks like this:

Code: Select all

MODE 4
*FX 20 0
VDU 23,128,28,28,8,127,8,20,34,65
VDU 23,129,&3C,&3C,&18,&FF,&18,&3C,&66,&C3
?&7F=128:?&87=129
*/INVADER

The first two lines are probably unnecessary, but are left over from testing.
The two VDU 23 command define the man from the User Guide and a more porty version, well, the food around here has started to get more calorific!
The next line tells the program which user defined characters to use, don't change the addresses written to, but you could change 128 to ASC"*" and 129 to ASC"." if you wanted to make the game harder!
The last line just * runs Invaders.

There is no prize for the best graphics, but I would love to see what you come up with.
A friend of mine made a special version of space invaders in the early PC days with user replaceable gfx, but I don't want to see any of those!
I think we should be fairly safe in 8x8 monochrome!

Thanks to Phil for suggesting this.

PS As you may know, I'm not good at playing well with the OS, so let me know what I have broken and I'll try and fix it.

[sPhilMainwaring]

Great job Tricky ... It was supposed to be a surprise at the next pixel graphics workshop

I've got lots of other plans along these lines ... I'll PM you my e-mail address if you could reply with yours

Cheers

[tricky]

Sorry, I hope that it hasn't spoiled too many people's surprise.

[tricky]

key remapping added and autobooting when invader is in SWROM slot 0 fixed.
The shooting doesn't sound quite like I remembered it, but it is the same in the 2021 version!

[tricky]

Fixed occasional corrupt text in loading.