08405: t1000hx, t1000sx, t1000tx, t1000rl, t1000tl2, t1000sl2: Screen corruption when setting screen mode 0 in BASIC

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
08405	Graphics	Minor	Always	Aug 25, 2022, 11:40	Sep 8, 2022, 02:20

Tester	einstein95	View Status	Public	Platform	MAME (Official Binary)
Assigned To		Resolution	Open	OS	Linux (64-bit)
Status [?]	Confirmed			Driver	pc/tandy1t.cpp
Version	0.246	Fixed in Version		Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	08405: t1000hx, t1000sx, t1000tx, t1000rl, t1000tl2, t1000sl2: Screen corruption when setting screen mode 0 in BASIC
Description	Screen mode 0 in BASIC should enable the 80x25 character screen mode (using 8x16px characters, for a resolution of 640x400), but trying to use it in MAME instead overwrites the screen with corruption and spams the log with "[:pcvideo_t1000] t1000_gfx_1bpp_update_row"
Steps To Reproduce	Boot the computer with Tandy MS-DOS Run BASIC Type "screen 0" then press enter
Additional Information	Before the "t1000_gfx_1bpp_update_row" log spam, the last message is "[:pcvideo_t1000:mc6845_t1000] M6845: Mode Control 02 is not supported!!!"
Github Commit

Flags
Regression Version
Affected Sets / Systems	t1000hx, t1000sx, t1000tx, t1000rl, t1000tl2, t1000sl2

Attached Files	0000.png (22,507 bytes) Aug 25, 2022, 11:40 Uploaded by einstein95 The screen with corruption

No.20489 Robbbert Moderator Aug 27, 2022, 14:51	I'm having great difficulty getting these systems to recognise anything in drive A, when choosing a software-list item. It doesn't show in the File Manager. t1000rl tries to start some kind of desktop but hangs. I also tried some loose software with mixed success. Please provide the exact steps in how you got your machine to run BASIC.
No.20507 Foxhack Tester Sep 7, 2022, 07:24 edited on: Sep 7, 2022, 07:26	Try mame t1000hx -flop1 msdos33sl2. Give it a bit so it boots, it'll ask you to enter the date and time, just hit enter. At the prompt, just type basic, hit enter, and wait a bit for it to load. GW-BASIC 3.20 will load, there you can type "screen 0" (no quotes) and you'll get the screen shown above. OR, just press F10 (with UI controls disabled) at the basic prompt, seems to enter 'screen 0,0,0"? I managed to get a glance of that before the screen corrupted.
No.20510 Robbbert Moderator Sep 8, 2022, 02:19	With that sequence I was able to confirm the report. You can enter another screen command either before or after that one, and the problem is gone.