FUN27-Assembly language routines

by Lance Wolstrup


Machine Language routine to scroll protect 1 - 7 lines on Model 4.

0607  LD      B,7     ;OPTION 7 OF @VDCTL SVC
0E01  LD      C,1     ;C=LINES TO SCROLL PROTECT
                      ;C MUST BE 1 - 7. FOR NO SCROLL PROTECT USE 8
3E0F   LD     A,15    ;@VDCTL SVC NUMBER
EF     RST    28H     ;EXECUTE @VDCTL
C9     RET            ;RETURN TO CALLER



Convert HEX to DECIMAL

HEX   DEC
06    6
07    7
0E    14
01    1       ;THIS IS THE BYTE THAT WILL BE CHANGED ACCORDING
              ;TO HOW MANY LINES IS TO BE PROTECTED
3E    62
0F    15
EF    239
C9    201


The decimal numbers can now be used in BASIC DATA statements.
