Indexed addressing mode and Reset0Ref

[pierreboberg]

Hi,
trying to do a simple rutine to print 4 dotes using Indexed addressing. 1 dot on 0,0 1 dot on 2,2 1 dot on 4,4 and 1 dot on 8,8.
And I need to reset the "pen" . Where am I thinking wrong? :-) (Print Hello is only to check the branch i working)

Regards Pierre


; here the cartridge program starts off



LDA #0

STA $C900

STA $C910

LDA #2

STA $C901

STA $C911

LDA #4

STA $C902

STA $C912

LDA #8

STA $C903

STA $C913

LDA $FE

STA $C904

main:

                   JSR      Wait_Recal           ; Vectrex BIOS recalibration

                   JSR      Intensity_5F         ; Sets the intensity of the

                                                 ; vector beam to $5f



LDY $C900

LDX $C910

draw:

JSR Reset0Ref

LDA ,Y+

CMPA $FE

BEQ done

LDB ,X+

JSR Dot_d

BRA draw

done:



                   LDU      #hello   ; address of string

                   LDA      #$10                 ; Text position relative Y

                   LDB      #-$50                ; Text position relative X

                   JSR      Print_Str_d          ; Vectrex BIOS print routine

                   BRA      main                 ; and repeat forever



hello:

DB "HELLO"

DB $80

[kokovec]

It's been a while since I've drawn dots but from what I remember..
First you have to set the scale factor.

LDB #$[scale]
STB <VIA_t1_cnt_lo ;Set scale factor

After Reset0Ref I believe you need to move the pen with something like

ldd #00
jsr Moveto_d

You may also need to add a short delay after calling Reset0Ref to allow the integrators to "settle".

[D-Type]

Here's a Forth test word I wrote to display dots using all the different dot drawing BIOS functions.

It might look unfamiliar, but the first 5 or 7 lines will give you the basic idea of what works for me.


\ Dot drawing tests.
: dots \ -- ;
  begin
     _Wait_Recal
     $40 VIA_t1_cnt_lo c!   \ Set scaling factor
     _Intensity_5F          \ Set intensity, works with default dwell value

     \ Display four dots, starting from centre, moving in a line right and up
     _Dot_here              \ Dot in centre of screen

     $10 8 _Dot_d           \ Dot $10 right, $8 up from previous dot

     $1020 pad !            \ Setup yx co-ord parameter in pad
     pad _Dot_ix            \ Dot $20 right, $10 up from previous dot

     $2040 pad !            \ Setup yx co-ord parameter in pad
     5 pad _Dot_ix_b        \ Dot $40 right, $20 up, with dwell 5

     \ Displays an approximate mirrored version of Ursa Major
     _Reset0Ref
     DOTS_LIST_PACKET _Dot_List_Reset \ Display dot list, using terminator

     \ Displays an approximate mirrored version of Ursa Major, 2nd time
     _Reset0Ref
     6 Vec_Misc_Count c!    \ 7 dots total, starting from 0
     DOTS_LIST _Dot_List    \ Display dot list, using counter

     key?
  until
  key drop
;


[Malban]

Simple answer:

The loading of the x/y registers is "extended" not "immediate"...



LDY $C900
LDX $C910



must be



LDY #$C900
LDX #$C910



Cheers

[kokovec]

I wonder if Malban could hear the sound of my hand slapping my forehead from Germany?

[pierreboberg]

Malban thank you :-) that solved the problem.