Aquarius Portal Demo: Now Available to Run on MAME 0.232

[chjmartin2]

Hi,

 

I haven't really had time or space to work on anything fun for the Aquarius in a really long time.  Recently I saw there was a new emulator available and then I found out that @Pernod has been hard at work updating MAME to have better Aquarius support including Supercart I bankswitching compatibility.  I couldn't contain my excitement!  (I am not on Facebook, so sadly, can't share this work there but maybe somebody could cross post.)  Anyway, with @jaybird3rd's and @Pernod's help I was able to update my Portal demo to be compatible with MAME 0.232.  I am so excited because it completely works including a faithful reproduction of the 1 bit audio engine and border audio sensitive effect.  The only odd result is that it seems to be going a bit too fast versus the hardware result, it isn't too off-putting but for sure there is something going on there.  I remember on real hardware I had to count t-states and tweak the 1 bit sampling rate to get it just right, technically it is a 1 bit audio stream running at 100,889 HZ.   I use a program on a PC to perform the 16 bit 100kHZ audio to 1 bit conversion using Sigma Delta Modulation and then have to t-state count to get a balanced audio output.  

 

Here is a Youtube video of the demo running on original hardware back in the day (I seem to remember being able to embed Youtube videos here but can't see how to do it, so I'll use a link):

 

Portal Demo Version 2

 

Here is a Mame Direct Capture of the latest version of the Demo:

 

Portal Demo Direct MAME Capture

 

Finally here is the ROM itself for you to try on MAME 0.232.  Important tip, grab the ROM set here.  It goes into the MAME ROM directory.  When you run MAME you get a menu and if all you have is Aquarius then you can select Available and it will show up when you have the ROM set correct.  Then run it selecting Start Empty, and here is where I got tripped up, you have to hit SCROLL LOCK to enable the menu, then TAB and then go to File Manager, select the Cartridge port and then the .BIN file to run.  I left those steps in the capture video in case you want to see visually what to do.  

 

PortalDemo.zip

 

Future plans include creating a generic audio conversion tool for use that will allow output at various ROM sizes instead of just the full megabyte, conversion of my movie player to be compatible with MAME 0.232, and other things that I likely haven't thought of yet.  I am excited to get back to doing some work on the Aquarius, which for now will have to be through emulation because having two young twin girls (both turned 3 in March) I just do not have the space for on-machine development.  Words of encouragement certainly help with motivation.  

 

Thanks,

 

Chris

Edited July 3, 2021 by chjmartin2

[carlsson]

So for those of us who are unfamiliar with the technology, is this a 1 MB cartridge where you bank switch certain blocks into the memory map all the time, and then read the data in order to create the 1-bit sample playback? Cool thing! So would you say that you get roughly 1.5 minutes of audio from 1 MB minus the executable program? About 10 kilobyte per second?

[chjmartin2]

2 hours ago, carlsson said:

So for those of us who are unfamiliar with the technology, is this a 1 MB cartridge where you bank switch certain blocks into the memory map all the time, and then read the data in order to create the 1-bit sample playback? Cool thing! So would you say that you get roughly 1.5 minutes of audio from 1 MB minus the executable program? About 10 kilobyte per second?

Yes, 8k of player data and the image, and then 1016k of audio data.  It is exactly 82.489 seconds of audio and a bit rate of 100,899 or 12.32 kbytes per second.

[Pernod]

Really happy to see you persevered with getting your ROM running in MAME, and even happier to see how it compares with real hardware.

 

Whilst the bank switching went in quite a few months ago the border effects were only implemented in May, so the 0.232 release is the first to include them. You're the first user to showcase this as I was only able to do limited testing myself.

 

I'm aware the video timing is not quite 100% and will gladly update it when more definitive timings are known.

[chjmartin2]

4 hours ago, Pernod said:

Whilst the bank switching went in quite a few months ago the border effects were only implemented in May, so the 0.232 release is the first to include them. You're the first user to showcase this as I was only able to do limited testing myself.

Woot... Great news.  What is the max audio rate output by the emulator?  So if we are running audio at 100khz and it is working, if we were to up that to a higher rate, at what rate would we break the emulator?

[Pernod]

3 minutes ago, chjmartin2 said:

What is the max audio rate output by the emulator?  So if we are running audio at 100khz and it is working, if we were to up that to a higher rate, at what rate would we break the emulator?

Why would it break the emulator? If you can push more data on real hardware then MAME should do the same.

[chjmartin2]

Just now, Pernod said:

Why would it break the emulator? If you can push more data on real hardware then MAME should do the same.

Clearly I do not understand how the sound emulation works.  At some point we would hit the limit of the sound card on the system.  I know my sound card can play up to 384 Khz.  I can't get near that anyway, only getting up to 120KHz and not feeling like I have the Z80 talent to do better than that, so merely an academic question clearly.