Improve Video Hardware Reset

- This change avoids clearing the screen every time an OS reset occurs.  A non-destructive VDC reset is now performed that leaves the screen contents and cursor position unchanged.
- If an application overwrites the video RAM, then the screen may contain garbage upon return to OS.  However, the console will still be functional and the user can just press enter a few times to clear the screen.

ReadMe.md

@@ -3,7 +3,7 @@
 **RomWBW ReadMe** \
 Version 3.5 \
 Wayne Warthen  ([wwarthen@gmail.com](mailto:wwarthen@gmail.com)) \
-28 Feb 2024
+03 Apr 2024
 
 # Overview
 

ReadMe.txt

@@ -1,6 +1,6 @@
 RomWBW ReadMe
 Wayne Warthen (wwarthen@gmail.com)
-28 Feb 2024
+03 Apr 2024
 
 
 

Source/Doc/SystemGuide.md

@@ -1327,7 +1327,7 @@ specified (set to 0 for default/not specified). Video Mode (E) values
 are specific to each VDA.  The returned Status (A) is a standard HBIOS 
 result code.
 
-If the hardware and driver support it, you can specify a Font Bitmap 
+If the hardware and driver supports it, you can specify a Font Bitmap 
 (HL) buffer address containing the character bitmap data to be loaded 
 into the video processor.  The buffer **must** be located entirely in the 
 top 32K of the CPU memory space. HL must be set to zero if no character 
@@ -1372,10 +1372,10 @@ data, then Font Bitmap (HL) will be set to zero on return.
 | B: 0x42                                | A: Status                              |
 | C: Video Unit                          |                                        |
 
-Performs a soft reset of the specified Video Unit (C). Will clear the 
-screen, home the cursor, and restore active attribute/color to defaults.
-Keyboard will be flushed.  The current video mode will not be changed. 
-The returned Status (A) is a standard HBIOS result code.
+Performs a non-destructive reset of the specified Video Unit (C).  
+Should re-initialize the video hardware without destroying the screen 
+contents or cursor position.  The current video mode will not be 
+changed. The returned Status (A) is a standard HBIOS result code.
 
 ### Function 0x43 -- Video Device (VDADEV)
 

Source/HBIOS/cvdu.asm

@@ -148,6 +148,15 @@ CVDU_VDAINI:
 	; RESET VDA
 	; CURRENTLY IGNORES VIDEO MODE AND BITMAP DATA
 	CALL	CVDU_VDARES		; RESET VDA
+	LD	A,$0E			; ATTRIBUTE IS STANDARD WHITE ON BLACK
+	LD	(CVDU_ATTR),A		; SAVE IT
+	LD	DE,0			; ROW = 0, COL = 0
+	CALL	CVDU_XY			; SEND CURSOR TO TOP LEFT
+	LD	A,' '			; BLANK THE SCREEN
+	LD	DE,$800			; FILL ENTIRE BUFFER
+	CALL	CVDU_FILL		; DO IT
+	LD	DE,0			; ROW = 0, COL = 0
+	CALL	CVDU_XY			; SEND CURSOR TO TOP LEFT
 	XOR	A			; SIGNAL SUCCESS
 	RET
 
@@ -160,17 +169,6 @@ CVDU_VDAQRY:
 	RET
 
 CVDU_VDARES:
-	LD	A,$0E			; ATTRIBUTE IS STANDARD WHITE ON BLACK
-	LD	(CVDU_ATTR),A		; SAVE IT
-
-	LD	DE,0			; ROW = 0, COL = 0
-	CALL	CVDU_XY			; SEND CURSOR TO TOP LEFT
-	LD	A,' '			; BLANK THE SCREEN
-	LD	DE,$800			; FILL ENTIRE BUFFER
-	CALL	CVDU_FILL		; DO IT
-	LD	DE,0			; ROW = 0, COL = 0
-	CALL	CVDU_XY			; SEND CURSOR TO TOP LEFT
-
 	XOR	A
 	RET
 

Source/HBIOS/ef.asm

@@ -570,6 +570,13 @@ EF_VDAINI:
 	LD	A,L
 	OR	H
 	CALL	NZ,EF_LOADFONTS
+
+	CALL	EF_CLEARALL
+	CALL	EF_LOADCSTYLE
+	LD	DE,0
+	LD	(EF_VDA_OFFSET),DE
+	CALL	EF_VDASCP
+
 	XOR	A
 	RET
 ;
@@ -586,13 +593,8 @@ EF_VDAQRY:
 ;
 EF_VDARES:
 ; VIDEO RESET
-; SOFT RESET, CLEAR SCREEN, HOME CURSOR, RESTORE ATTRIBUTE/COLOR DEFAULTS
+; SOFT RESET
 ;
-	CALL	EF_CLEARALL
-	CALL	EF_LOADCSTYLE
-	LD	DE,0
-	LD	(EF_VDA_OFFSET),DE
-	CALL	EF_VDASCP
 	XOR	A
 	RET
 ;

Source/HBIOS/gdc.asm

@@ -161,8 +161,7 @@ GDC_VDAQRY:	; VIDEO INFORMATION QUERY
 	RET
 ;
 GDC_VDARES:	; VIDEO SYSTEM RESET
-	; *** TODO: RESET VIDEO SYSTEM HERE, CLEAR SCREEN,
-	; CURSOR TO TOP LEFT, CLEAR ATTRIBUTES
+	; *** TODO: RESET VIDEO SYSTEM HERE
 	XOR	A
 	RET
 ;

Source/HBIOS/term.asm

@@ -54,6 +54,9 @@ TERM_ATTACH:
 	LD	A,(TERM_DEVCNT)		; GET NEXT DEVICE NUMBER TO USE
 	LD	B,A			; PUT IT IN B
 	PUSH	HL			; SAVE VDA INSTANCE DATA PTR
+;
+	LD	A,C			; VIDEO UNIT TO A
+	LD	(TERM_VDADEV),A		; SAVE IT
 ;
 	; SETUP EMULATOR MODULE FUNC TBL ADDRESS BASED ON DESIRED EMULATION
 	; EMULATOR PASSES BACK IT'S FUNC TBL ADDRESS IN DE
@@ -99,22 +102,18 @@ TERM_RESET:
 	RET
 ;
 TERM_RESET1:
-	; CALL EMULATOR INITDEV FUNCTION
-  #IF (VDAEMU == EMUTYP_TTY)
-	CALL	TTY_INITDEV
-  #ENDIF
-  #IF (VDAEMU == EMUTYP_ANSI)
-	CALL	ANSI_INITDEV
-  #ENDIF
-;
-	XOR	A
-	RET
+	; RESET THE ATTACHED VDA DEVICE
+	LD	B,BF_VDARES		; FUNC: RESET
+	LD	A,(TERM_VDADEV)		; GET VDA UNIT NUM
+	LD	C,A			; PUT IN C
+	JP	ANSI_VDADISP		; CALL THE VDA DRIVER
 ;
 ;======================================================================
 ; TERMINAL DRIVER PRIVATE DATA
 ;======================================================================
 ;
 TERM_DEVCNT	.DB	0		; TERMINAL DEVICE COUNT
+TERM_VDADEV	.DB	0		; ATTACHED VDA UNIT
 ;
 ;======================================================================
 ; EMULATION MODULES

Source/HBIOS/tms.asm

@@ -249,7 +249,7 @@ TMS_INIT:
 TMS_INIT1:
 	CALL 	TMS_CRTINIT		; SETUP THE TMS CHIP REGISTERS
 	CALL	TMS_LOADFONT		; LOAD FONT DATA FROM ROM TO TMS STRORAGE
-	CALL	TMS_VDARES1
+	CALL	TMS_CLEAR		; CLEAR SCREEN, HOME CURSOR
 #IF (TMSMODE == TMSMODE_N8)
 	CALL	PPK_INIT		; INITIALIZE PPI KEYBOARD DRIVER
 #ENDIF
@@ -335,6 +335,7 @@ TMS_VDAINI:
 	; RESET VDA
 	; CURRENTLY IGNORES VIDEO MODE AND BITMAP DATA
 	CALL	TMS_VDARES		; RESET VDA
+	CALL	TMS_CLEAR		; CLEAR SCREEN
 	XOR	A			; SIGNAL SUCCESS
 	RET
 
@@ -350,30 +351,16 @@ TMS_VDARES:
 #IF (CPUFAM == CPU_Z180)
 	CALL	TMS_Z180IO
 #ENDIF
-	CALL	TMS_CRTINIT
+	CALL	TMS_CRTINIT1A
 #IF (!USELZSA2)
 	; WE WANT TO RELOAD THE FONT ON RESET, BUT THIS IS NOT CURRENTLY
 	; POSSIBLE WHEN FONT COMPRESSION IS IN USE.
-	CALL	TMS_LOADFONT
+	CALL	TMS_LOADFONT		; RELOAD FONT
+	LD	A,$FF			; REMOVE
+	LD	(TMS_CURSAV),A		; ... SAVED CURSOR CHAR
+	CALL	TMS_SETCUR		; SET NEW CURSOR
 #ENDIF
-;
-; ENTRY POINT USED BY TMS_INIT TO AVOID DUPLICATE CALL TO TMS_CRTINIT
-; AND TMS_Z180IO.
-;
-TMS_VDARES1:
-	LD	DE,0			; ROW = 0, COL = 0
-	CALL	TMS_XY			; SEND CURSOR TO TOP LEFT
-	LD	A,' '			; BLANK THE SCREEN
-	LD	DE,TMS_ROWS * TMS_COLS	; FILL ENTIRE BUFFER
-	CALL	TMS_FILL		; DO IT
-	LD	DE,0			; ROW = 0, COL = 0
-	CALL	TMS_XY			; SEND CURSOR TO TOP LEFT
 	XOR	A
-	DEC	A
-	LD	(TMS_CURSAV),A
-	CALL	TMS_SETCUR		; SET CURSOR
-
-	XOR	A			; SIGNAL SUCCESS
 	RET
 
 TMS_VDADEV:
@@ -634,6 +621,8 @@ TMS_CRTINIT1:
 	LD	A,D
 	OR	E
 	JR	NZ,TMS_CRTINIT1
+;
+TMS_CRTINIT1A:
 ;
 	; INITIALIZE VDU REGISTERS
 	LD 	C,0			; START WITH REGISTER 0
@@ -655,6 +644,26 @@ TMS_CRTINIT2:
     	RET
 ;
 ;----------------------------------------------------------------------
+; CLEAR SCREEN AND HOME CURSOR
+;----------------------------------------------------------------------
+;
+TMS_CLEAR:
+	LD	DE,0			; ROW = 0, COL = 0
+	CALL	TMS_XY			; SEND CURSOR TO TOP LEFT
+	LD	A,' '			; BLANK THE SCREEN
+	LD	DE,TMS_ROWS * TMS_COLS	; FILL ENTIRE BUFFER
+	CALL	TMS_FILL		; DO IT
+	LD	DE,0			; ROW = 0, COL = 0
+	CALL	TMS_XY			; SEND CURSOR TO TOP LEFT
+	XOR	A
+	DEC	A
+	LD	(TMS_CURSAV),A
+	CALL	TMS_SETCUR		; SET CURSOR
+;
+	XOR	A			; SIGNAL SUCCESS
+	RET
+;
+;----------------------------------------------------------------------
 ; LOAD FONT DATA
 ;----------------------------------------------------------------------
 ;
@@ -707,7 +716,7 @@ TMS_STACK	.DW	0
 ;
 ; VIRTUAL CURSOR IS GENERATED BY DYNAMICALLY CHANGING FONT GLYPH
 ; FOR CHAR 255 TO BE THE INVERSE OF THE GLYPH OF THE CHARACTER UNDER
-; THE CURRENT CURSOR POSITION.  THE CHARACTER CODE IS THEN SWITCH TO
+; THE CURRENT CURSOR POSITION.  THE CHARACTER CODE IS THEN SWITCHED TO
 ; THE VALUE 255 AND THE ORIGINAL VALUE IS SAVED.  WHEN THE DISPLAY
 ; NEEDS TO BE CHANGED THE PROCESS IS UNDONE.  IT IS ESSENTIAL THAT
 ; ALL DISPLAY CHANGES BE BRACKETED WITH CALLS TO TMS_CLRCUR PRIOR TO

Source/HBIOS/vdu.asm

@@ -165,6 +165,12 @@ VDU_VDAINI:
 	; RESET VDA
 	; CURRENTLY IGNORES VIDEO MODE AND BITMAP DATA
 	CALL	VDU_VDARES		; RESET VDA
+	LD	DE,0
+	LD	(VDU_OFFSET),DE
+	CALL	VDU_XY
+	LD	A,' '
+	LD	DE,1024*16
+	CALL	VDU_FILL
 	XOR	A			; SIGNAL SUCCESS
 	RET
 
@@ -176,13 +182,6 @@ VDU_VDAQRY:
 	RET
 
 VDU_VDARES:
-	LD	DE,0
-	LD	(VDU_OFFSET),DE
-	CALL	VDU_XY
-	LD	A,' '
-	LD	DE,1024*16
-	CALL	VDU_FILL
-
 	XOR	A
 	RET
 

Source/HBIOS/vga.asm

@@ -180,18 +180,7 @@ VGA_VDAINI:
 	; RESET VDA
 	; CURRENTLY IGNORES VIDEO MODE AND BITMAP DATA
 	CALL	VGA_VDARES	; RESET VDA
-	XOR	A		; SIGNAL SUCCESS
-	RET
-
-VGA_VDAQRY:
-	LD	C,$00		; MODE ZERO IS ALL WE KNOW
-	LD	D,VGA_ROWS	; ROWS
-	LD	E,VGA_COLS	; COLS
-	LD	HL,0		; EXTRACTION OF CURRENT BITMAP DATA NOT SUPPORTED YET
-	XOR	A		; SIGNAL SUCCESS
-	RET
 
-VGA_VDARES:
 	LD	A,$07		; ATTRIBUTE IS STANDARD WHITE ON BLACK
 	LD	(VGA_ATTR),A	; SAVE IT
 	XOR	A		; ZERO (REVERSE, UNDERLINE, BLINK)
@@ -205,6 +194,18 @@ VGA_VDARES:
 	LD	DE,0		; ROW = 0, COL = 0
 	CALL	VGA_XY		; SEND CURSOR TO TOP LEFT
 
+	XOR	A		; SIGNAL SUCCESS
+	RET
+
+VGA_VDAQRY:
+	LD	C,$00		; MODE ZERO IS ALL WE KNOW
+	LD	D,VGA_ROWS	; ROWS
+	LD	E,VGA_COLS	; COLS
+	LD	HL,0		; EXTRACTION OF CURRENT BITMAP DATA NOT SUPPORTED YET
+	XOR	A		; SIGNAL SUCCESS
+	RET
+
+VGA_VDARES:
 	LD	HL,$0404 | VGA_89BIT; SET VIDEO ENABLE BIT
 	CALL	VGA_SETCFG	; DO IT
 

Source/HBIOS/vrc.asm

@@ -117,18 +117,6 @@ VRC_VDAINI:
 	; RESET VDA
 	; CURRENTLY IGNORES VIDEO MODE AND BITMAP DATA
 	CALL	VRC_VDARES	; RESET VDA
-	XOR	A		; SIGNAL SUCCESS
-	RET
-
-VRC_VDAQRY:
-	LD	C,$00		; MODE ZERO IS ALL WE KNOW
-	LD	D,VRC_ROWS	; ROWS
-	LD	E,VRC_COLS	; COLS
-	LD	HL,0		; EXTRACTION OF CURRENT BITMAP DATA NOT SUPPORTED YET
-	XOR	A		; SIGNAL SUCCESS
-	RET
-
-VRC_VDARES:
 	XOR	A		; CLEAR ATTRIBUTES (REV VIDEO OFF)
 	LD	(VRC_ATTR),A	; SAVE IT
 	DEC	A		; INIT CUR NESTING, INIT TO HIDDEN
@@ -143,7 +131,18 @@ VRC_VDARES:
 	LD	DE,0		; ROW = 0, COL = 0
 	CALL	VRC_XY		; SEND CURSOR TO TOP LEFT
 	CALL	VRC_SHOWCUR	; NOW SHOW THE CURSOR
-;
+	XOR	A		; SIGNAL SUCCESS
+	RET
+
+VRC_VDAQRY:
+	LD	C,$00		; MODE ZERO IS ALL WE KNOW
+	LD	D,VRC_ROWS	; ROWS
+	LD	E,VRC_COLS	; COLS
+	LD	HL,0		; EXTRACTION OF CURRENT BITMAP DATA NOT SUPPORTED YET
+	XOR	A		; SIGNAL SUCCESS
+	RET
+
+VRC_VDARES:
 	XOR	A		; SIGNAL SUCCESS
 	RET
 

Source/ver.inc

@@ -2,7 +2,7 @@
 #DEFINE	RMN	5
 #DEFINE	RUP	0
 #DEFINE	RTP	0
-#DEFINE BIOSVER	"3.5.0-dev.23"
+#DEFINE BIOSVER	"3.5.0-dev.24"
 #define rmj	RMJ
 #define rmn	RMN
 #define rup	RUP

Source/ver.lib

@@ -3,5 +3,5 @@ rmn	equ	5
 rup	equ	0
 rtp	equ	0
 biosver	macro
-	db	"3.5.0-dev.23"
+	db	"3.5.0-dev.24"
 	endm