Jump to content
IGNORED

Dragon's Lair


Tursi

Recommended Posts

Tursi, I have a few SMT sockets of the right type for this if you need one to build a test board to verify the chip works perfectly before you solder it in place on another board. . .

I made some in the early days using the same adapter that my EPROM programmer uses, since it was nicely broken out to pins already. I've only soldered a couple of chips for testing the final PCBs.

 

post-12959-0-42383900-1545293620_thumb.jpg

  • Like 8
Link to comment
Share on other sites

I don't know what I was expecting when I grabbed the demo the other day. I hadn't seen any video clips before I ran it for myself.

 

I certainly wasn't expecting such clear sound, dithering so finely tuned that everything was perfectly watchable, or animation that was so smooth. This is an incredible accomplishment.

  • Like 5
Link to comment
Share on other sites

Can anyone make a video of the demo?

 

Sure, give me a couple of minutes. I'll use my video screen capture program. I not exactly sure how to play the game yet, so it might be a short demo! Either way you'll get to see the graphics and hear the audio.

 

Hopefully this will not take more than 15 minutes... BRB.

  • Like 1
Link to comment
Share on other sites

 

Sure, give me a couple of minutes. I'll use my video screen capture program. I not exactly sure how to play the game yet, so it might be a short demo! Either way you'll get to see the graphics and hear the audio.

 

Hopefully this will not take more than 15 minutes... BRB.

 

Thank you! :) :thumbsup:

Link to comment
Share on other sites

It supports the F18A for reduced flicker

 

Yep.

 

The Ti's bitmap mode has two separate tables - one for the pixels, and one for the colors. By necessity, they are updated separately, but the TI is too slow to update them both in a single frame (in frame, it takes about 6 video frames). This means that you can watch it paint, and you can see when the pixels change, then the colors. To reduce that effect, I paint the video in four chunks, so that the pattern and color writes are closer together. But it still takes more than a frame, meaning you get a sort of a 'sparkling' or 'twinkling' effect when the raster happens to catch an in-between state.

 

With the F18A, I take advantage of the high-speed GPU and extra RAM to mitigate that to almost zero. The CPU first writes the pattern to an offscreen buffer, so it doesn't affect the display. The GPU then quickly moves the data to its own private memory, and the CPU simultaneously uploads the color data. When it's done, the GPU can use its high speed plus direct VRAM access to quickly write the pattern and color bytes one after the other. The twinkle is still possible if the raster catches the exact right moment, but it's very, very, very rare.

 

The good news is that since releasing the demo I solved a problem that had been baffling me related to the flicker, and now the raw 9918A version is also substantially improved. I'll hopefully get a hardware video out this weekend to show it. I have a standalone filter that can reduce the changes to the pattern table between frames, which greatly reduces the twinkle -- the program reports changing 45% of the pixels for the better on Dragon's Lair. (And this is not a lossy change, the end result is the same). I'll update my video conversion tools to include this filter soon, too, and I updated all my sample converted videos. ;)

  • Like 9
Link to comment
Share on other sites

 

 

How and when can we pre-order Tursi?

 

I have until March, I may try to ask for an extension. But in the meantime, here's the plan:

 

Once I have assembled one of the PCBs and it works, I will start taking orders. I should be able to ship them as they are assembled. The cost is going to be approximately $100 for cart, box, and label. The box will hopefully be double-sided (retro themed and modern themed), and the labels definitely are. I haven't decided whether to ship the box flat and labels separate, or ask preference, or what. I may let you decide. To clarify - no manual.

 

So - for those who want to save up - start saving now. This is your warning. :)

 

I am only planning to build 100 units. Some units may fail and I may not make it to 100, but that's what I have parts for. Building more is dubious, as the flash chips got hard to find (unless there was a new run of them...)

  • Like 1
Link to comment
Share on other sites

This is an 8MB non-inverted ROM cartridge image. It should run on hardware and should run on an emulator that supports 8MB worth of the standard banking scheme. (The scheme goes up to 32MB). (The final cart boots from GROM for 2.2 compatibility. This demo does not so isn't 2.2 compatible.)

 

I tried to run Ciro's RPK in MAME, but unfortunately it keeps crashing the emulator. The reason was that the paged378 cartridge type only allows for 64 banks of 8K (512K), since it is using the 74LS378 (which offers six flipflops, hence 2^6 states).

 

Also, the paged377 type allows for 256 banks due to the 74LS377 offering 8 FF.

 

So it is not really surprising that this puts the emulator into trouble, as the buffers are far too small to handle the ROM contents (so I'm getting a memory corruption).

 

I assumed these 74LS377/378/379 circuits are still in use for these cartridges, but for 32M you require 4096 banks, which would need a circuit with 12 FF. Or is that solved by a custom programmed chip? Anyway, I'd have to introduce a new cartridge type for it.

Edited by mizapf
  • Like 2
Link to comment
Share on other sites

You could just put a pair of 378s on a cartridge board--or even a 377 and a 378 (pretty much the most you could get without synthesizing additional bits, as you only have 13 bits to play with on the bus). Still, that would get you one huge cartridge, one that would have more available space than every single TI cartridge made. . .combined into one monstrous image. The only issue would be finding an appropriate 5V tolerant 64M EPROM (or Flash) chip.

Link to comment
Share on other sites

The Gigacart uses 15 bits by taking the 13 bits from the address bus plus two bits from the data bus. It also maps the last 256 bytes of the flash to GROM at >8000. An alternate CPLD load skips the GROM and offers 17 address bits (13 from the address bus and 4 from the data bus). The flash size is 128MB.

 

While I'm using a CPLD, it's just an extension of the same 378 circuit. In fact ArcadeShopper already has a demo cart in his possession that does 4MB. ;) It's not difficult to add more bits to the latch even with discrete logic - the main issue is the number of chips starts to go up. :)

 

The CPLD has the secondary benefit of doing the 3.3v to 5v conversion, so it's a really handy way to do it all on a single chip.

 

I'm using the Spansion S29GL01 (128MBx8).. they also make a 64MB version that last time I looked was a little more available.

 

So far as MAME goes, it probably should check the size of the file it's loading, but it's not terribly critical to support this. I don't think I'm allowed to release the ROM image anyway, and I doubt anyone else will adapt my design.

  • Like 1
Link to comment
Share on other sites

It's my thread, so I guess I'm allowed to spam it, but I was also looking at the 74LS259, which has also got 8 latches, or the 74FCT16373, which is a 5v tolerant 3v latch with 16 bits in one chip. (I went with the CPLD cause I still needed to do voltage conversion for the data and other address lines).

 

So.. the mechanism might be a better determinism of the cartridge type than the /actual/ TTL logic chip that drives it, cause there's more than one way to achieve the same results.

  • Like 3
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...