Category : BASIC Source Code
Archive   : QB_VGA.ZIP
Filename : VGASCROL.BAS

'Text Mode Scroller Text - By Rich Geldreich 1992
'This program may not work on some VGA's.
'Sorry for no documentation, just grab yourself a VGA reference and
'you'll know what's going on. (boy, am I helpfull)
DEFINT A-Z
SCREEN 0: WIDTH 40
OUT &H3D4, 9: OUT &H3D5, INP(&H3D5) OR 128
OUT &H3D4, &H13: OUT &H3D5, 42
SplitScreen = 32
OUT &H3D4,7:OUT &H3D5,(INP(&H3D5) AND 239) OR (SplitScreen AND 256)*16
OUT &H3D4,9:OUT &H3D5,(INP(&H3D5) AND 191) OR (SplitScreen AND 512)*32
OUT &H3D4, &H18: OUT &H3D5, SplitScreen AND 255
a = INP(&H3DA): OUT &H3C0, &H10: OUT &H3C0, INP(&H3C1) OR 32
St$ = "&09Howdy strangers.... This is &8ERich Geldreich's&09 "
St$ = St$ + "simple text mode scroller. How do you like it? "
St$ = St$ + SPACE$(40) + "%7 Look!" + SPACE$(40)
St$ = St$ + "%2 I can change the speed %3too! &8E Wow! "
St$ = St$ + "Look at the pretty colors... &0F " + SPACE$(10)
St$ = St$ + "Sorry I couldn't show you more. Since PostIt! has been "
St$=St$+"banned from the quik_bas conference, I can't give out any "
St$ = St$ + "object or data files... &8C[plug mode off]&0F "
St$=St$+"That's too bad... (&8CPsst!&0F The moderator hasn't "
St$=St$+"said anything about &8BDEBUG&0F scripts yet... I wonder if "
St$ = St$ + "they're Ok?"
St$ = St$ + SPACE$(40) + "&01Thanks for watching!" + SPACE$(40)
StPos = 1
ScreenPan = 0: ScreenPanSpeed = 3
Top = 41: Bottom = 41: ScreenStart = 0
DEF SEG = &HB800
a$ = "Press escape to quit."
a = 10 * 168 + 9 * 2
FOR B = 1 TO LEN(a$): POKE a, ASC(MID$(a$, B, 1)): a = a + 2: NEXT
DO
OUT &H3D4, &HD: OUT &H3D5, (ScreenStart AND 255)
OUT &H3D4, &HC: OUT &H3D5, (ScreenStart \ 256) + 16
WAIT &H3DA, 8
OUT &H3C0, &H33: OUT &H3C0, ScreenPan
ScreenPan = ScreenPan + ScreenPanSpeed
IF ScreenPan > 7 THEN
ScreenPan = ScreenPan - 8
DO
Char = ASC(MID$(St$, StPos, 1))
IF Char = 37 THEN
ScreenPanSpeed = VAL(MID$(St$, StPos + 1, 1))
StPos = StPos + 2
ELSEIF Char = 38 THEN
Attribute = VAL("&H" + MID$(St$, StPos + 1, 2))
StPos = StPos + 3
ELSE
EXIT DO
END IF
LOOP
StPos = StPos + 1: IF StPos >= LEN(St$) THEN StPos = 1
POKE 8192 + Top * 2, Char
POKE 8192 + Top * 2 + 1, Attribute
POKE 8192 + Bottom * 2, Char
POKE 8192 + Bottom * 2 + 1, Attribute
ScreenStart = ScreenStart + 1
IF ScreenStart = 42 THEN ScreenStart = 0
Top = Top + 1
IF Top = 42 THEN Top = 0
Bottom = Bottom + 1
IF Bottom = 83 THEN Bottom = 41
END IF
LOOP UNTIL INKEY$ = CHR$(27)
WIDTH 80