Hi,
I'm trying to write to print a character in screen 0 mode 80 columns).
I have hl registry equals to 0 and I'd expect to have my charater printed in position 0 (In basic is LOCATE 0,0) with this code:
Quote:
ld a,l
di
out (c),a
ld a,h
ei
out (c),a
Instead the character printed in position 1 (BASIC LOCATE 1,0).
I don't understand why.
If I set ht to 79 (HEX 4f) the character is printed into the first column of the second row (BASIC LOCATE 0,1)
It seems an offset of 1 character...
ld hl,Hello_TXT ; Load the address from the label Hello_TXT into HL.
call Print ; Call the routine Print below.
ret
Print:
ld a,(hl) ; Load the byte from memory at address indicated by HL to A.
or a ; Same as CP 0 but faster.
ret z ; Back behind the call print if A = 0
call CHPUT ; Call the routine to display a character.
inc hl ; Increment the HL value.
jr Print ; Relative jump to the address in the label Print.
; Message data
Hello_TXT: ; Set the current address into label Hello_TXT. (text pointer)
db "Hello world!",0 ; Zero indicates the end of text.
