CGA bug : prohibition game

[Altheos]

Describe the bug There's a rendering error using CGA graphic card and the game Prohibition (Infogrames). This game is using a CGA trick to do smooth scroll but screen is corrupted using Pcem. Screen corruption is easily observable on start screen.

To Reproduce Steps to reproduce the behavior:

1. Run prohi
2. Launch game choosing "Other" as video adapter and slow or high as speed
3. Launch game using spacebar then see error

Expected behavior smooth scroll and no glitches

Screenshots

Emulator configuration

• Machine: AMI 286 Clone
• CPU: Intel 286 10 Mhz
• Graphics/sound cards: CGA
• Installed OS : PCDOS 6.1

Host machine

• OS: Windows 10
• Emulator version : v17

[sarah-walker-pcem]

Accesses CRTC at ports 3d0/3d1 instead of 3d4/3d5. Works on real hardware due to incomplete address decode.

I'm guessing this won't work on every CGA clone.

[sarah-walker-pcem]

Fixed in c82cd20.

[Altheos]

Thanks for the fix.