MiSTer and FPGA

Following a request from a user on the MiSTer forum and since I was looking at making some changes to the Scramble core anyway I decided to add support for the game Cavelon.

It uses rom banking which had to be added in, and once I got that working I discovered that I also needed to add a new sprite banking method as well.

Once the pull request has been merged you will be able to play this difficult game on the MiSTer.

(well I have not managed to complete the first level yet anyway)

The original sound hardware for Cosmo has been reverse engineered from schematics generated by The Guru of Mame fame and has been added to the core on MiSTer

The original hardware runs at 333Khz which is way too fast for the audio output on MiSTer (maximum 96Khz) and sounded wrong at the correct speed. (due to lost sample changes, and trying to resample it at different rates did not improve it much)

So I have changed this clock to 192Khz and averaged the output to the DAC over two samples.

This results in the effects being about 4 notes lower and slightly slower than the original, however in comparison to a video of the real thing I didn’t notice a difference!

The problem with the high score saving for Gorf and Wizard of Wor should now be resolved.

You can now see the settings menu when the OSD button is pressed, although background will be black or just stars, which allows you to change the settings once more.

Reloading the scores will no longer cause other unwanted side effects.

I have removed the downloads for the images with High Score saving for the moment as I have found a couple of problems during further testing.

• The CRT blanks out when the game is paused, which makes it very difficult to change the settings. (HDMI continues to work but not many people have HDMI monitors in their cabinets)
• The save file also interferes with other functions of the game depending upon when it was saved. (speech does not work, automatically starts the game etc.)

They will be back when I sort out these problems!

I have added two new images to the “Putting it Together” page (here) that now implement the NVRam that could be used with the hardware. The games that support this are “Gorf” and “Wizard of Wor”.

These versions will allow you to save the high scores to the SDRam card whenever they change.

To do this you need to press the OSD button before you switch off. (I prefer to do this on the attract screen) and if the scores have changed since they were loaded you should get a “Saving ….” popup before the normal menu appears.

As a side line, when in the OSD menu the game will now pause. So if you need a quick drink (or something else) in the middle of a long session you can affectively use this to pause the game and resume when you return with a second press on the OSD button.

There are a few new DIP settings added to Gorf, so I decided I may need to explain them. For further information see the “Changing the Settings” page (here)

It seems that Coin Op Collection have completed a Snow Bros core for MiSTer before I did. Not really surprising since I have taken ages on this one. I had suffered from one of the same problems as they did, so at least I was on the right track.

For the moment I will look into the missing sound circuits on Cosmo (Space Invaders hardware) and then better analogue sound for Galaxian.

The 68000 based core I was working on is not totally redundant as it may be revisited later with a view to running a different game!

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I have made a change to the checkout form for the shop, a phone number is now required. This is because shipping to some countries with Royal Mail now requires this and it saves me having to email you to ask for one.