MiSTer and FPGA

An extra option or two has been added to the DIP settings on “Gorf” and “Gorf (Program 1)”

Both now have an “Autocoin” option. This can be used instead of freeplay and it will automatically insert the correct number of coins when you press Start 1 or 2 to let you start with 2 (low) or 4 (High) ships (depends on the ships per credit setting)

“Gorf” has an addition “Rank” option. This will allow better players (not me!) to start at a rank other than “Space Cadet” for practising those advanced moves. You can select any of the ranks or certain Mission numbers.

Grab the updated image here. (updated 2nd July 2026)

The classic shoot’em up Space Firebird has been completed as a core and added to MiSTer.

It uses the weirdest video hardware of any game I have ever seen, and this core was created in an attempt to understand the circuitry a little better.

The sprites are in 3-3-2 colour, via a lookup table (same as Galaxian and many others), but then there is a separate circuit that can pull these colours to ground via different resistors which adds 4 levels of intensity that is used when the ships appear to make them look like they are fading in.

Stars are static but a register under CPU control can vary the intensity of them a little to give the appearance of them flashing.

Incidentally, when in cocktail mode and the picture is inverted for player two, the stars stay in the same place as they did for player one. That circuit is not aware that the screen has been altered.

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!