Screen Store and Recall Basic Routines for VDC in C128

5 rem vdc screen store/recall demo routines
10 printchr$(147):print"using the two routines given in this sample,"
20 print:print"one can store and recall the vdc screen of c128"
30 print:print:print"for related questions, you can e-mail to ilker ficicilar"
40 print:print"filker@newton.physics.metu.edu.tr"
50 fori=0to14:print:next
60 print"-"tab(32)"press a key"tab(79)"-"chr$(19)tab(79)" " 70 geta$:ifa$=""goto70
80 gosub300:printchr$(147)"press a key to recall the screen back" 90 geta$:ifa$=""goto90
100 gosub200:printchr$(19):fori=0to23:print:next 110 print"issue the 'cont' command to redraw it" 120 end
130 goto100
199 end
200 bank15:rem recalling the vdc 80 screen 210 sysdec("cdcc"),0 ,18:sysdec("cdcc"),0,19 220 sysdec("cdcc"),16,32:sysdec("cdcc"),0,33 230 sysdec("cdcc"),160,24:fori=0to15:sysdec("cdcc"),255,30:next:return 300 bank15:rem storing the vdc 80 screen 310 sysdec("cdcc"),16,18:sysdec("cdcc"),0,19 320 sysdec("cdcc"),0 ,32:sysdec("cdcc"),0,33 330 sysdec("cdcc"),160,24:fori=0to15:sysdec("cdcc"),255,30:next:return 390 :
400 rem related vdc registers
410 :
420 rem 19,18 = destination (19 = low byte) 430 rem 33,32 = source (33 = low byte) 440 rem 24 = copy/fill selection
450 rem 30 = number of bytes to be copied 460 :
470 rem vdc memory map
480 :
490 rem $0000-$07ff = screen memory
500 rem $0800-$0fff = attributes memory 510 rem $1000-$1fff = unused (but we used it to store the copy) 520 rem $2000-$3fff = font data (1 char = upper 8 byte of 16 bytes) 530 :
540 rem related kernal calls
550 :
560 rem $cdcc = write to vdc register x the value a 570 rem $cdda = read the vdc register x into a 580 :

Ilker Ficicilar
ilkerf@geocities.com

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