Assembly experiment: bouncing block

Thanks, I like it here
I'm now going to experiment with some scrolling on screen 1. Using name and pattern tables.

Looks great, nice job! Also congrats on the MSX!

Thanks, I'm going to order a MegaFlashRom at https://www.msxcartridgeshop.com/ to transfer my programs to the real MSX. I also found a second hand Arcade joystick from Suzo to make my setup complete.

Hi PbK71
this section of your code could be optimized as you have done at displaysprite:
Try setting the VRAM start address using SETWRT and use out and the self increment of the VRAM pointer in the VDP

; --- UPDATE Y AND X COORDINATE in VRAM ---
ld HL,SPRITEAT ; VRAM address to write attributes of sprite 0
ld a,(y+1) ; y-coordinate = high byte of word y
call WRTVRM ; write to VRAM
INC HL
ld a,(x) ; x-coordinate
call WRTVRM ; write to VRAM

ld HL,SPRITEAT+4 ; VRAM address to write attributes of sprite 1
ld a,(y+1) ; y-coordinate = high byte of word y
call WRTVRM ; write to VRAM
INC HL
ld a,(x) ; x-coordinate
call WRTVRM ; write to VRAM

ld HL,SPRITEAT+8 ; VRAM address to write attributes of sprite 2
ld a,(y+1) ; y-coordinate = high byte of word y
call WRTVRM ; write to VRAM
INC HL
ld a,(x) ; x-coordinate
call WRTVRM ; write to VRAM

ld HL,SPRITEAT+12 ; VRAM address to write attributes of sprite 3
ld a,(y+1) ; y-coordinate = high byte of word y
call WRTVRM ; write to VRAM
INC HL
ld a,(x) ; x-coordinate
call WRTVRM ; write to VRAM

Hello ARTRAG,

Thanks for the advice. I tried this, but ran into the problem that after writing the x and y coordinate of a sprite I either have to skip 2 bytes (sprite pattern and color) or 'rewrite' those values again. My attempt on skipping them was this:

; --- UPDATE Y AND X COORDINATE in VRAM ---
              ld HL,SPRITEAT  	; VRAM address to write attributes of sprite 0
	      call SETWRT		; enable VDP to write	
	      ld c,0x98			; load port 0x98 to write to in c
              ld a,(y+1)		; y-coordinate = high byte of word y
              out(c),a     		; write to VRAM  
              ld a,(x)	    	; x-coordinate
              out(c),a     		; write to VRAM  

              ld HL,SPRITEAT+4  ; VRAM address to write attributes of sprite 1
	     call SETWRT		; enable VDP to write
              ld a,(y+1)		; y-coordinate = high byte of word y
              out(c),a     		; write to VRAM  
              ld a,(x)	    	; x-coordinate
              out(c),a     		; write to VRAM  

              ld HL,SPRITEAT+8  ; VRAM address to write attributes of sprite 2
			  call SETWRT		; enable VDP to write
              ld a,(y+1)		; y-coordinate = high byte of word y
              out(c),a     		; write to VRAM  
              ld a,(x)	    	; x-coordinate
              out(c),a     		; write to VRAM  

              ld HL,SPRITEAT+12 ; VRAM address to write attributes of sprite 3
              call SETWRT		; enable VDP to write
              ld a,(y+1)		; y-coordinate = high byte of word y
              out(c),a     		; write to VRAM  
              ld a,(x)	    	; x-coordinate
              out(c),a     		; write to VRAM  

I could adjust it to rewriting sprite pattern and color. So, something lik this I gues:

; --- UPDATE Y AND X COORDINATE in VRAM ---
              ld HL,SPRITEAT  	; VRAM address to write attributes of sprite 0
	      call SETWRT		; enable VDP to write	
	     ld c,0x98			; load port 0x98 to write to in c
              ld a,(y+1)		; y-coordinate = high byte of word y
              out(c),a     		; write to VRAM  
              ld a,(x)	    	; x-coordinate
              out(c),a     		; write to VRAM 
              ld a,0			; sprite pattern 0
              out(c),a     		; write to VRAM                         
              ld a,1			; color 1
              out(c),a     		; write to VRAM  

              ld a,(y+1)		; y-coordinate = high byte of word y
              out(c),a     		; write to VRAM  
              ld a,(x)	    	; x-coordinate
              out(c),a     		; write to VRAM  
              ld a,4			; sprite pattern 1 (starts at 4)
              out(c),a     		; write to VRAM           
              ld a,10			; color
              out(c),a     		; write to VRAM 
       
            ... and so on ....

Which one is preferred? Or is there another solution?

@santiontanon: If I would your solution I would have to update the x and y coordinate 4 times when thay change? Because then I would have to store it 4 each sprite separate.