UpdateBuff:
DI
LD HL,1B00h ; point to start of SA in vram.
LD A,L
OUT (99h),A
LD A,H
OR $40
EI
OUT (99h),A
LD B,128 (127?) ; amount of bytes to output.
LD C,98h ; destination is vdp data port.
LD HL,C000h ; source is start of sat buffer.
UpdateBuff_Loop:
OUTI
JR NZ,UpdateBuff_Loop
RET
or:
xor a
di ; set VRAM address to 1800h
out (99h),a ; lower byte 00
ld a,1Bh + 040h ; upper byte 1Bh with flag to set the bus in write mode (1B00-1B7F VRAM: Sprite Attributes (128))
ei
out (99h),a ; note that this is protected by the ei instruction
LD B,128 (127?)
LD C,98h
ld hl,C000h ; 128 byte Sprite Attributes Buffer in WRAM
loop:
outi ; send the data (HL) to port 98h (podobnie jak w SMS mialem OTIR i byl problem, musialem OUTI uzyc wolniejsze)
jp nz,loop ; the inner loop is exactly 29 cycles. If you are not in VBLANK this is the max speed for msx1.
I am a little surprised that first thing you teach a beginning programmer is to bypass one of the foundations of the MSX standard, the BIOS. I think there is no need to do that, unless you want to squice 100% out of the hardware. But for a beginning programer this is not very important. Or am I missing something ?
xor a
di ; set VRAM address to 1800h
out (99h),a ; lower byte 00
ld a,1Bh + 040h ; upper byte 1Bh with flag to set the bus in write mode (1B00-1B7F VRAM: Sprite Attributes (128))
ei
out (99h),a ; note that this is protected by the ei instruction
ld bc,8098h
ld hl,C000h ; 128 byte Sprite Attributes Buffer in WRAM
loop:
outi ; send the data (HL) to port 98h
jp nz,loop ; the inner loop is exactly 29 cycles.
I would like to change the BACKGROUND color to black, but I have no idea how it works?
CHGCLR (0062H) *1
Function: changes the screen colour
Input:
A for the mode
FORCLR (F3E9H) for foreground color
BAKCLR (F3EAH) for background color
BDRCLR (F3EBH) for border colour
Output: none
Registers: all
ld a,colvalue?
call 0062H
What is "F3EBH"? Do I need to write value in this address?
I noticed that the sprite screen position starts with X. $ 20 on the left edge of the screen. The maximum value to the right is FF and it does not reach the right edge of the screen (mode0 / screen 1)
From what I can see the XY coordinates are 8 bits so I wonder how to set the sprite on the right edge of the screen?
BIOS routine CHGCLR uses FORCLR, BAKCLR and BDRCLR values.
Therefore, it is used like this:
ld a, 12 ; dark green, for example
ld (BDRCLR), a
call CHGCLR
Please note that BDRCLR is applied immediately, and BAKCLR will be seen when you change screen mode (not sure if also in SCREEN 0/1). FORCLR makes sense in SCREEN 0/1 if you use BIOS routines to print text, for example.
