'===========================================================================
' Subject: BACK SWITCHING                    Date: 03-21-96 (21:23)       
' Author:  Earl L. Montgomery                Code: QB, PDS                
' Origin:  FidoNet QUIK_BAS Echo           Packet: GRAPHICS.ABC
'===========================================================================
 'This program demonstrates how to use bank switching so that you
 'can poke the entire 720X540X256 screen rather than use the slow
 'ROM Bios interrupt SETPIXEL. This code will work with Video
 '7 graphic chips. If you do not have a video7 graphic chip but
 'would like to run this demo. Please give me the name of your
 'graphic card/chip and I should be able to furnish you with the
 'correct code so it will run on your system.

 '$INCLUDE: 'qb.bi'
 DIM inreg AS RegType
 DIM outreg AS RegType
 DEFLNG A-Z
 inreg.ax = &H6F05
 'inreg.bx = &H66: flag = 66:   '640x400x256
 'inreg.bx = &H67: flag = 67:   '640x480x256
 inreg.bx = &H68: flag = 68:    '720x540x256
 'inreg.bx = &H69:flag = 69:    '800x600x256
 CALL interrupt(&H10, inreg, outreg)
 DEF SEG = &HA000
 FOR x = 0 TO 65535
 POKE x, 4
 NEXT
bank1:
 OUT &H3C4, &HE8
 OUT &H3C5, &H10
 FOR x = 0 TO 65535
 POKE x, 184
 NEXT
bank2:
 OUT &H3C4, &HE8
 OUT &H3C5, &H20
 FOR x = 0 TO 65535
 POKE x, 4
 NEXT
bank3:
 OUT &H3C4, &HE8
 OUT &H3C5, &H30
 FOR x = 0 TO 65535
 POKE x, 3
 NEXT
bank4:
 OUT &H3C4, &HE8
 OUT &H3C5, &H40
 FOR x = 0 TO 65535
 POKE x, 143
 NEXT
 IF flag = 66 OR flag = 67 THEN GOTO bank5notneeded
bank5:
 OUT &H3C4, &HE8
 OUT &H3C5, &H50
 FOR x = 0 TO 65535
 POKE x, 3
 NEXT
bank5notneeded:
SLEEP (100)
inreg.ax = &H3
CALL interrupt(&H10, inreg, outreg)
CLS : END