[Homebreviews - part 21]

Thanks for the reviews.

 

In Beef Drop "more" mode gives you access to 4 new boards after you clear the existing ones.

 

--Ken

[Some progress on Space Invaders 7800]

(1) They probably could be characters or sprites but the data will probably need to be in RAM. I am guessing sprites would be best since I don't think having them be characters buys you anything. Unfortunately due to the layout of data for either that probably needs a 2K block (although you can use any unused sprite areas for other things).

[b*nQ]

I think you'd need 80 two-line zones, not 40, unless you want to use less than half of the screen vertically. Since each zone would take a minimum of 9 bytes (three for the DLL entry, and six for a minimal single-item display list) you're down to 300 bytes before you've even started. Just not going to work.

 

The only way to achieve a usable half-resolution screen on the 7800 is to either use extra hardware (as in Rescue on Fractalus) or else have a display list which gets patched for each scan line. I've tried that approach, and it works, but the code required for emulation is different from that required for a real machine. I was looking before at Missile Command, btw; QIX would have somewhat different requirements but the same principles would apply.

Yea you're right with the 80. I divided by two twice. I think I was going to shrink it a little more horizontally. But yes, it seemed like a lot of work and a lot of compromises (small less colorful board) to fit it into 4K RAM. That's primarily the reason I didn't start it.

[b*nQ]

Alternatively, it may be good to draw the QIX at half vertical resolution. Unfortunately, there's no way to do that with standard RAM other than by using beam-chasing code. There's not necessarily anything wrong with beam-chasing (it can save memory for display lists) but I don't know what emulators handle it accurately.

I had planned to do it at half vertical resolution in bitmapped mode. The playfield on 5200 QIX is around 128x80 [4 color] and would need about 2.5K for just the screen data.

Bad part it I would need 40 two row high zones for the playfield. (first entry would have row 0 and row 1, second entry would have row 1 and row 2, third entry would have row 2 and row 3). The QIX would be bitmapped (so they would have to be red, blue, or white and would be double line rez). Other items would be "sprites" (sparx and fuse). Luckily they are small and would not occupy too many zones at once each.

[b*nQ]

Qix on the 2600 would require extra RAM. Even with extra RAM, some concessions would be needed. Especially given the risk of trademark issues, it may be better to use a slightly different game design (most notably replacing the bouncing bunch of lines with something else bouncy). The bouncing lines would be neat, but the only way I can see those working would be to use a 104x192 two-color "flickerscreen" bitmap. That might look okay, but it would require a lot of RAM.

 

If the bouncy object were a more conventional sprite, then it might be possible to use a color-striped playfield for the background and get by with something like a SARA-size RAM.

RAM would even be pretty tight on the 7800, but I did calculate a board size close the 5200 version should be possible (narrow playfield and graphics rows would have to be doubled up).

[7800 thoughts]

Hmm... If there's one thing I've learned about the 7800 is it is CPU limitted. At least with a virtual bitmap you're not having to contantly rebuilt the display lists. The DMA cycle stealing should also be a little easier to predict.

 

Note: there's no 2LK for the 7800, so you're limitting yourself to the only half of the screen height with 128x96.

 

I was considering starting on a project where I was going to have a bitmapped display with double height lines (kinda like graphics 7 (antic D?) on 8 bits). It would require a display list list entry for every two scan lines though.

[VCS on VCR]

You should be able to swith the VCR to antenna or air mode vs. cable and the local uhf channel will be on the correct channel.

[Qbert and Beef Drop WIP]

As far as I remember the meatball colors could be better.

meatball?????

Ok meatball seems to be wrong word.

Maybe hamburger is correct?

I mean the meat part of the burger.

Ahh, That sounds better.

When you said meatball, I was thinking of what was round, and the only thing I could think of was the pickles.

 

--Ken

[Qbert and Beef Drop WIP]

As far as I remember the meatball colors could be better.

meatball?????

[Qbert and Beef Drop WIP]

I haven't played Q-Bert on my PAL device yet (only emu).

Maybe I'll check it next weekend.

Do you implemented different PAL/NTSC palettes for Beefdrop?

Some colors could look better on PAL IMHO.

But it’s a cool version anyway

If there are any colors that seem off, let me know and I can try to swap them out in PAL mode with different colors.