I recently got a Star Force PCB and as I like to have a free play setting on my cabs and boards I decided to create a free play mod. The game I have is a Star Force (encrypted set 1) PCB using the 315-5069 encrypted z80 CPU.
The original PCB has various coin settings using bits set on DSW1 depending on whether 1 or 2 coins have been inserted but no free play setting. If you insert a coin then a screen is displayed indefinitely asking you to press P1 or P2 to begin. The changes I made include just hitting P1 or P2 to begin the game, display "FREE PLAY" on the attract screen and to never ask for a coin input.
I had to code the mod using encrypted hex and during testing I found the MAME debugger was showing a different input hex value to what the real board was sending, presumably due to it being decrypted. To make the game work on the PCB I needed to add an XOR D0 to my code but this means the patch files don't work when running in MAME (see below).
I have only tested this mod on my Star Force (encrypted set 1) PCB and I am sure that the other versions I have coded should work fine. In the zip files below you will find the code contained in patch files with full instructions on how to update your roms - there are no roms in the zip files.
I have used patch files to ensure the correct rom is being patched as the patcher program will report an error if you have selected the wrong rom to update. The patch files follow the same naming convention as used by MAME. If you want to apply the free play mod to MAME, it is a 1 byte fix by editing the relevant patch file as specified below.
Star Force (starforc - unencrypted)
Star Force (starforce - encrypted set 1) – for MAME set $16D3 to A8 in patch file starfore.003
Star Force (starforca - encrypted set 2) – for MAME set $16D4 to 80 in patch file 3.bin
Star Force (starforcb - encrypted bootleg) – for MAME set $16D4 to 88 in patch file a4.8j
If anyone has a bootleg or encrypted set 2 and is willing to try the mod, please let me know how you get on.
The original PCB has various coin settings using bits set on DSW1 depending on whether 1 or 2 coins have been inserted but no free play setting. If you insert a coin then a screen is displayed indefinitely asking you to press P1 or P2 to begin. The changes I made include just hitting P1 or P2 to begin the game, display "FREE PLAY" on the attract screen and to never ask for a coin input.
I had to code the mod using encrypted hex and during testing I found the MAME debugger was showing a different input hex value to what the real board was sending, presumably due to it being decrypted. To make the game work on the PCB I needed to add an XOR D0 to my code but this means the patch files don't work when running in MAME (see below).
I have only tested this mod on my Star Force (encrypted set 1) PCB and I am sure that the other versions I have coded should work fine. In the zip files below you will find the code contained in patch files with full instructions on how to update your roms - there are no roms in the zip files.
I have used patch files to ensure the correct rom is being patched as the patcher program will report an error if you have selected the wrong rom to update. The patch files follow the same naming convention as used by MAME. If you want to apply the free play mod to MAME, it is a 1 byte fix by editing the relevant patch file as specified below.
Star Force (starforc - unencrypted)
Star Force (starforce - encrypted set 1) – for MAME set $16D3 to A8 in patch file starfore.003
Star Force (starforca - encrypted set 2) – for MAME set $16D4 to 80 in patch file 3.bin
Star Force (starforcb - encrypted bootleg) – for MAME set $16D4 to 88 in patch file a4.8j
If anyone has a bootleg or encrypted set 2 and is willing to try the mod, please let me know how you get on.
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