09168: ct486 [Supaplex, Prehistorik 2]: Hardware scrolling ("pel panning") problems in games

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
09168	Gameplay	Major	Always	8 days ago	8 days ago

Tester	vanfanel	View Status	Public	Platform	MAME (Self-compiled)
Assigned To		Resolution	Open	OS	Linux (64-bit)
Status [?]	Direction Needed			Driver	pc/ct486.cpp
Version	0.277	Fixed in Version		Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	09168: ct486 [Supaplex, Prehistorik 2]: Hardware scrolling ("pel panning") problems in games
Description	Some games using VGA hardware scrolling (a technique known as "pel panning" back in the DOS days) present severe problems in the ct486 driver. I have tried different VGA card models in slot1 (svga_s3, vga, mach64), but the results are always the same: -Supaplex: Score are on the lower part of the screen scrolls along with the main play area, then wraps to it's initial position, then repeats. This scrore area should remain still. Happens both with original game and with the speed-fixed version commonly known as SPFIX63. -Prehistorik 2: When the game starts, the scrolling background before the level loads, as well as the map, also scroll in jagged steps and "sway" back and forth periodically.
Steps To Reproduce	Simply run "Supaplex" or "Prehistorik 2" with the ct486 driver.
Additional Information	There were similar problems in the 86box emulator with "pel panning", but they were fixed time ago. This is the issue where these problems were reported in 86box: https://github.com/86Box/86Box/issues/462 And this is the commit where this was fixed: https://github.com/86Box/86Box/commit/ac0a1ee327de845bcfe193778c24780839310b7f I really hope this makes the fix easy to implement in MAME, too! :)
Github Commit

Flags
Regression Version
Affected Sets / Systems	ct486 [Supaplex, Prehistorik 2]

Attached Files	MANUAL.PDF (62,143 bytes) 8 days ago Uploaded by PL1 Supaplex manual -- copy protection codes on last page.

No.23263 Robbbert Moderator 8 days ago	Those games as floppy disks are not included in any suitable software list, so someone would need to search for them. The ct486 itself does nothing useful at boot. I imagine that various slots need to be filled, together with at least a boot disk. You need to specify all these things, step by step.
No.23264 PL1 Tester 8 days ago edited on: 8 days ago	Found Supaplex disk images (original and SPFIX63 versions) online and got them working on an already-configured MAME v0.262 ct486 Win95 setup. MAME startup command line: mame ct486 -ramsize 16M -hard1 win95 -board3:ide:ide:1 cdrom -isa2 sblaster_16 -isa1 svga_s3 Mount floppy image on A: drive. Copy all game files from A:\ to C:\supaplex\ To launch the game, double click on C:\supaplex\SPFIX63.exe (no copy protection) or SUPAPLEX.exe. (copy protection codes are on the last page of the manual) As you scroll the playfield left/right, the bottom panel does stutter but does not wrap around. i.e. playfield and panel both move two steps together then the panel snaps back to the correct position. The spfix63.doc readme file mentions not running the game under Windows, so that may be a contributing factor. The best way to play Supaplex is using plain DOS, not any Win9x DOS box, and not the DOS from the Win9x shut-down menu! To properly test this, I need to do a fresh install of current MAME with a software list DOS HDD, install the SB16 from software list, copy the game files from the floppy .img file to the HDD, and maybe edit autoexec.bat + config.sys per the manual. Scott

No.23263

Robbbert

Moderator

8 days ago

Those games as floppy disks are not included in any suitable software list, so someone would need to search for them.

The ct486 itself does nothing useful at boot. I imagine that various slots need to be filled, together with at least a boot disk. You need to specify all these things, step by step.

No.23264

PL1

Tester

8 days ago

edited on: 8 days ago

Found Supaplex disk images (original and SPFIX63 versions) online and got them working on an already-configured MAME v0.262 ct486 Win95 setup.

MAME startup command line: mame ct486 -ramsize 16M -hard1 win95 -board3:ide:ide:1 cdrom -isa2 sblaster_16 -isa1 svga_s3

Mount floppy image on A: drive.
Copy all game files from A:\ to C:\supaplex\
To launch the game, double click on C:\supaplex\SPFIX63.exe (no copy protection) or SUPAPLEX.exe. (copy protection codes are on the last page of the manual)

As you scroll the playfield left/right, the bottom panel does stutter but does not wrap around. i.e. playfield and panel both move two steps together then the panel snaps back to the correct position.

The spfix63.doc readme file mentions not running the game under Windows, so that may be a contributing factor.

The best way to play Supaplex is using plain DOS, not any Win9x DOS box, and not the DOS from the Win9x shut-down menu!

To properly test this, I need to do a fresh install of current MAME with a software list DOS HDD, install the SB16 from software list, copy the game files from the floppy .img file to the HDD, and maybe edit autoexec.bat + config.sys per the manual.

Scott