Routines
Prev: 63162 Up: Map Next: 63219
63203: Move virtual cursor (bitmap) to display file for coordinates x=C, y=B and load address into HL
Used by the routines at 39216, 39366, 41504, 41545, 47193, 47326, 61297, 61336, 61418, 61521, 63691 and 63740.
Input
B y-coordinate (characters)
C x-coordinate (characters)
Output
HL Virtual cursor (bitmap) display file address
63203 LD A,B Load y-coordinate into A
63204 AND 24 AND 24 to determine which third of the bitmap memory we are in (A = 0, 8 or 16)
63206 ADD A,64 Load HL with display file address of start of appropriate third of display...
63208 LD H,A ...(16,384, 18,432 or 20,480)
63209 LD A,B Load y-coordinate back into A
63210 AND 7 AND 7 to determine which of the 8 character rows within the third we are interested in
63212 RRCA Multiply by 8 to get pixel row required...
63213 RRCA ...
63214 RRCA ...
63215 ADD A,C Add x-coordinate
63216 LD L,A Add to value currently in HL
63217 JR 63259 Store the updated address of bitmap virtual text cursor and return
Prev: 63162 Up: Map Next: 63219