Bally Astrocade on FPGA

[Macro]

Progress has been made on the Wizard or Wor front, I have added the sparkle circuit into the mix and it is now doing what I need it to.

for those who would like to know, it is currently using a different polynomial (so the stars will be in a different position to the real thing) since I seem to be having great trouble getting the correct one to give me anything but a sequence of FFFF (which shows no stars whatever!). Will fix that it due course.

Programming in FPGA land all the problems seem to be down to timing, everything seems to be happen too early or too late - it is easy enough to delay a signal, but quite tricky to make it happen earlier.

also, until I did this I never knew that the Z80 put additional information on the bus when you do an IN or an OUT command - the hardware actually writes to the sparkle registers by doing an IN command (that confused me for a while as well)

 

[LAZORIAN]

Amazing work!

 

[ataridude74]

Next up - Gorf!

(PLEASE!!!!!!!!!!!!!!!!!!!)

 

[bonehead]

Truly amazing!!!

 

[Macro]

It now has the correct polynomial in, but looks different from mame since I reset on the vsync, not on pixel 0

plus I need to do something about the 4 bit colour data, so thinking about how to make things brighter (without making existing colours darker) - have some ideas to test out.

not sure what one is next, I like robby roto, but then I also have gorf cab, so have to do that one

 

[Hurray Banana]

Excellent progress Mike

 

[DanP]

If you're taking votes then GORF please!

Great work so far Mike, keep it going!

 

[andyman]

Nice stuff Mike...I'll vote Gorf too then...probably the only way I'll ever get a working cab

 

[GadgetFreak]

until I did this I never knew that the Z80 put additional information on the bus when you do an IN or an OUT command - the hardware actually writes to the sparkle registers by doing an IN command (that confused me for a while as well)

I found this out (no pun intended) when I did my Berzerk multi.

This is looking really promising, these games are sadly missing from my collection, and when they do come up they are usually in the USA and cost a lot to ship let alone purchase.
And knowing your work I am sure they will be perfect!

 

[Pinge]

I also vote for Gorf, have a spare boardset just missing a working custom.

 

[Macro]

I added the lightpen interrupt (used by Gorf and Wizard, although Wizard doesn't seem any different with or without it) - and Gorf gets a little further, but boot loops since it is looking for something that isn't there (yet)

but ...

Roto now fires up and looks OK (no controls yet, so no idea what it does beyond attract mode - incidentally Roto is public domain, so I can even include the roms for it!)

 

[Macro]

Some progress with Gorf - I have found a problem which may explain why Gorf doesn't run, now trying to fix it!

Gorf uses the pattern board to initialise memory etc. and for some reason it is corrupting the ram (even though it seems to write to the screen without a problem!)

 

[bonehead]

Sound like you are on it. Keep up the work Mike!!!

 

[Macro]

I think I have fixed the memory corruption, but Gorf is still not happy - although I do get the odd visible screen flash and things like the high score are in the right place, just not for long

on the plus side, the minor graphic corruption on Space Zap has been fixed.

 

[Hurray Banana]

Love that roby screen. You may be responsible for rescuing many murdered roby rotos Mike, great progress

 

[Macro]

Gorf is a major pain

to start with, it sets all the colours to black whilst it draws the screen, so unless it works for long enough, you cannot see what it is doing

so, add some fake colours so I can see what is happening, and it goes loopy at random intervals in pattern board (some stuff appears where it should, some is all over the show - reason ... no idea, something is corrupting the various magic and pallette registers

but why does it only affect Gorf ? Space zap, robby and wizard all use the pattern board without any such problems - so trying to discover what is causing it.

 

[Hurray Banana]

That's a pain Mike, didn't Jamie Fenton say the noise effect came out of some code mistake, maybe it's related.

I wonder if she could throw some light on it

 

[Pinge]

I follow this thread with big interest, If you manage to fix a replacement for Gorf you deserve a Nobel Price in Game preservation.

 

[Macro]

I have just put the project in the MiSTer github, so it should be available to anyone who wants it.

Gorf still not working, but it means more people can look at the problem so hopefully it will get fixed. I will keep trying to sort it out, since I have a Gorf cab and a more reliable PCB would be a good thing.

 

[bonehead]

That’s very good work Mike. I’m sure the community will be appreciative of what you have done. Please stick with gorf as you know I love mine and would so much like to have a reliable modern board to put in it so it can live on.
Keep up the good work.
Cheers