Astro Fighter Freeplay/Attract Mode

[philmurr]

The last of my games (apart from some of the bronze age ones that don't have great scoring anyway) that doesn't have freeplay built in is Astro Fighter. Not really a classic but I used to play this in a department store in Holmeside Sunderland just in the doorway, and remember it very fondly.

It's got one of the most clunky "enter coin" routines with slow text being drawn when all you want to do is play the game, so I wanted to improve things.

A few hours later with my rusty 6502 coding and here is the finished product. It was a bit tricky as the game relies on non-maskable interrupt to signal when a coin is entered, so I've had to intercept all the separate demo screens and also disable coins being added when it's in freeplay mode.

There isn't a spare DIP switch to select normal/freeplay modes so I've used the "1 coin 2 credits" setting to be the freeplay mode.

Features:-

Prints "FREEPLAY" during game attract when in freeplay mode

Just walk up and press P1 or P2 start to begin a game

Doesn't display credits when in freeplay mode

That's kind of it, what more is there???

Code will be free of charge once fully play-tested, unfortunately you'll need to reprogramme 5 of the 6 game ROMS to get it working properly, but it is a nice addition to the game.

And the photos (all from Mame as it's not been tested on real hardware yet, but I can see no reason why it shouldn't work)

Demo mode

And finally the game playing, note that "FREEPLAY" is not displayed

 

[jonhughes]

Nice one Phil, I’ve got this board and me and the seller never found a way to coin it. Figured it had some coin on reset mode like a few of the other earlier games (like needed to be connected to a coin counter to credit). Anyway, I hope this will give free play and remove credits for me.jonhughes2020-01-22 21:31:02

 

[Digimon]

real nice.

 

[philmurr]

Nice one Phil, I’ve got this board and me and the seller never found a way to coin it. Figured it had some coin on reset mode like a few of the other earlier games (like needed to be connected to a coin counter to credit). Anyway, I hope this will give free play and remove credits for me.

Jon - it relies on a non-maskable interrupt to generate the coin up signal but there is a bit of logic to do this that could go wrong.

I’ll send you the code later on today for you to try.

 

[Digimon]

I am not sure, but will it work with the Zaccaria Astro Wars, too?

 

[philmurr]

I am not sure, but will it work with the Zaccaria Astro Wars, too?

Unfortunately not. It's a similar game but uses a different CPU (like so many Zacc copies do)

 

[jonhughes]

Nice one Phil, I’ve got this board and me and the seller never found a way to coin it. Figured it had some coin on reset mode like a few of the other earlier games (like needed to be connected to a coin counter to credit). Anyway, I hope this will give free play and remove credits for me.

Jon - it relies on a non-maskable interrupt to generate the coin up signal but there is a bit of logic to do this that could go wrong.

I’ll send you the code later on today for you to try.

Thanks Phil that would have been great but my programmer only supports 2716 at the least so I'm stumped.

 

[philmurr]

So I spent a bit of time chasing my tail over a bug I thought my code had introduced to the attract mode - turned out it had been there in the original code...

In attract mode when the ship fires and hits a yellow "fireball" (that you get 60 points for), it was adding 60 points to the P1 score in attract mode. It's a bug in the original game so I've added some extra code to remove said bug.

Freeplay/fixed bug code now available if anyone owns the game and wants it.

I've also done some extra coding to save the high score (no high score table, just a single high score) and I'll be testing it out on a 6502 single ROM/NVRAM board soon.

 

[BulkSlash]

Great work on this! It’s the game that got me into arcade machines years ago so it’s nice to see it getting some love.

 

[virtvic]

So I spent a bit of time chasing my tail over a bug I thought my code had introduced to the attract mode - turned out it had been there in the original code...

In attract mode when the ship fires and hits a yellow "fireball" (that you get 60 points for), it was adding 60 points to the P1 score in attract mode. It's a bug in the original game so I've added some extra code to remove said bug.

Freeplay/fixed bug code now available if anyone owns the game and wants it.

I've also done some extra coding to save the high score (no high score table, just a single high score) and I'll be testing it out on a 6502 single ROM/NVRAM board soon.

That's because you are a GOD.

 

[philmurr]

And this evening's pointless update, especially for Virtvic, who spotted that in the original game the "Advance Score" title for the high score table wasn't centred over the high score table itself, I've fixed that too.

Not as sraightforward as it may sound, as Astro Fighter uses an incredibly contrived way of writing text to the screen. Anyway, it's done

Seems like lots of people have never heard of, let alone played this game. Please give it a try, it's very addictive.

 

[Mc-Q]

Nice one Phil, I’ve got this board and me and the seller never found a way to coin it. Figured it had some coin on reset mode like a few of the other earlier games (like needed to be connected to a coin counter to credit). Anyway, I hope this will give free play and remove credits for me.

if you still cant credit this,

a number of old boards used a 3wire coinswitch for security,

you have normally open & normally closed coin inputs that must flip to clock a credit.

i get around these by putting a 7404 invertor between the normally open and normally closed inputs.

i cant remember which games, but i think they are in a cage - so sega G80 or bally-midway stuff may have needed it among others.