02646: pc_tenis: When starting a game, the screen quickly flashes garbage

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
02646	Graphics	Minor	Always	Nov 13, 2008, 01:17	Jan 28, 2022, 13:09

Tester	Luigi30	View Status	Public	Platform	MAME (Self-compiled)
Assigned To	kmg	Resolution	Fixed	OS
Status [?]	Resolved			Driver	nintendo/playch10.cpp
Version	0.128u3	Fixed in Version	0.241	Build
		Fixed in Git Commit	93bcb22	Github Pull Request #	#9220

Summary	02646: pc_tenis: When starting a game, the screen quickly flashes garbage
Description	When starting a game, after the player selects the difficulty, the screen flashes to a corrupt screen of 0s for one frame before the game kicks in.
Steps To Reproduce	1. Start a game 2. Select any difficulty
Additional Information
Github Commit

Flags
Regression Version
Affected Sets / Systems	pc_tenis

Attached Files	0000.png (7,126 bytes) Nov 13, 2008, 01:17

No.03038 Radwar Tester Nov 13, 2008, 01:54	Works fine for me with MAME 0128u3. I do get the "0" screen after selecting the difficulty level, but it appears and disappears in a fraction of a second, then the play field appears and the game runs normally.
No.03040 Tafoid Administrator Nov 13, 2008, 02:46	I'm very skeptical of one frame bugs like this - since it's all the same character, I would first assume it's some sort of intended clearing. I'll confirm this, but marked as possible pending some input from Devs and comparison to PC-10 version (home versions are not valid for comparison).
No.15849 MetalGod Senior Tester Nov 30, 2018, 12:01 edited on: Nov 30, 2018, 21:09	Different on the arcade. When selecting defficulty there's a fast change of some colors instead. Check 5:40:
No.15853 NekoEd Senior Tester Nov 30, 2018, 22:20	Removing the possible flag since we DO have a bug here, as we're not displaying the proper behavior.
No.19728 kmg Senior Tester Jan 28, 2022, 01:44	This is caused by the fact that the PC10 driver defaults to using all 4K of RAM allocated to the PPU nametables when in fact there's only 2K of RAM on actual hardware. Tennis must be briefly selecting one of the pages that is supposed to be a mirror and was never filled. You can get the same bug to happen on NES (NES tennisju set has identical roms with pc_tenis) by setting mirroring="4screen" in the softlist. Anyway, I've submitted a patch in https://github.com/mamedev/mame/pull/9220 which should fix things until there's a proper clean up.