PCL

Maria knows from the second byte in the header. If bits 0..4 are all 0, it's either a 5-byte header or a display list terminator. Otherwise, if any of bits 0..4 are set it's a 4-byte header. Funnily enough I'm thinking about going the other way. Everything I've done on the 7800 so far has been in assembler and I'm pondering giving 7800basic a try.

Yes, unfortunately it does. Every time Maria reads a byte of graphics data Sally is halted. So the more graphics you display, effectively the slower Sally gets. It is the same with the 5200/8-bit computers, but potentially worse on the 7800 since Maria can display a lot more graphic objects than ANTIC/GTIA. In the worst case, if you drive Maria to its maximum then essentially Sally does not run at all. There are 262 scanlines per NTSC frame (not all visible), so with a 224 scanline display and a maxed out Maria, Sally only runs during the 38 non-display scanlines effectively reducing the 1.79MHz clock rate to 0.26MHz. Of course you don't normally max out Maria but the more graphics you see on screen, the less time there is for code to run.

Yes, you get the end screen after completing round 8. It does get really fast in the later rounds but there is a tactical way to play the game.

I added 2 button support, so it should be playable with the Turbo 2000 in 7800 mode plus a few logic changes for when the hearts/diamonds appear and how long the Drebish Windows stay in place, to closer match the A8 original. drelbs.a78

From what I've read about the Turbo 2000 you can switch it between 2600 and 7800 mode. The controller should really do this automatically (it's how the europad and proline work) but I imagine it will work if you switch it to 2600 mode. I am currently modifying the code so that the hearts and diamonds more closely match when they appear in the original game. I will also add 2-button support so you shouldn't have to do this in the next (and hopefully final) release.

That's strange because it works on my PAL machine from DF. I have tried it with the europad, proline and a cx40 (my favourite for this game), pressing any of the triggers starts the game. As that is all the trigger is used for, I configure the controller for single trigger mode. What controller are you using?

Yes bonus points for the lady which can be useful. There are certain tactics which can help beat the game even with the insanely fast speeds of the last couple of rounds (7 & 8).

Yes, please let me know if you see any issues. I've tried to keep it as close as possible to the A8 original while trying to take advantage of the 7800's improved graphic capabilities. I'm not really one for releasing on cart as it's not my IP and adds more responsibility to a hobby. With Concerto, Dragonfly and the forthcoming GD there's plenty of ways to play it on real h/w.

This is a 7800 remake of one of my favourite A8 games. It is a 32K ROM with pokey@4000 (the same as Ballblazer) and seems to run OK on everything I've tested (Concerto/DF/A7800/BupSystem/JS7800/ProSystem). For anyone unfamiliar with the game there are instructions here: https://archive.org/details/drelbs-synapse As a remake the logic may not be 100% identical to the original but I think I have all the key aspects covered. drelbs.a78