The CBM510 runs programs in a non-system memory bank. It has its own zero page. Some things are copied from the system zero page; but, the cursor flags weren't copied. So, the cursor always blinked. That bug sometimes left cursor ghosts (reversed spaces) at the end of lines.
;------------------------------------------------------------------------------
; A table that contains values that must be transfered from the system zero
-; page into out zero page. Contains pairs of bytes, first one is the address
+; page into our zero page. Contains pairs of bytes; first one is the address
; in the system ZP, second one is our ZP address. The table goes into page 2,
-; but is declared here, because it is needed earlier.
+; but is declared here because it is needed earlier.
.SEGMENT "PAGE2"
.byte $9F, DEVNUM
.byte $CA, CURS_Y
.byte $CB, CURS_X
+ .byte $E6, CURS_FLAG
+ .byte $E7, CURS_BLINK
.byte $EC, CHARCOLOR
.endproc