Hello MSX community,

I am currently trying to code some very simple programs that use the VDP. I'm using tniasm and loading under MSX-Basic. (Yes, I know that's bad, but I'm just starting here!)

without further adieu....


here's one that's supposed to change to text 2 mode:

db $fe
dw start
dw eof
dw exec

org $8800

test2a: equ $04
test2b: equ $10

start:

hello: db "testing"

exec:

; set up registers 0 and 1 via port 1
ld a, test2a
out (1), a
ld a, $80
out (1), a
ld a, test2b
out (1), a
ld a, $81
out (1), a

ld bc, hello
call puts

.end: ret


puts:

ld a, (bc)
cp 0
ret z
call $a2
inc bc
jp puts
.end: ret

eof:


The text mode just stays the same!

Here's one that's supposed to load the palette with red, green, red, green ... until it's full, and then set the text to palette #0 and palette #1 (so, of course, it will be red and green). However, the screen remains blue and white!:

; set up VDP so only green and red are used

db $fe
dw start
dw eof
dw exec

org $8800


start:

loopvar: db 17
starttext: db "Starting... ", $0
redtext: db "Loading red... ", $0
greentext: db "Loading green... ", $0
testing: db "testing... ", $0


noblue: equ $00
red: equ $70
green: equ $07
nogreen: equ $00

exec:
; select palette # 0

ld a, $00
out (1), a ; palette # 0 in
ld a, $90
out (1), a ; register # 16

; for looping

call &theloop

; set up palette's register so palette can be automatically loaded from port 2
ld a, $01
out (1), a
ld a, $87
out (1), a

ld bc, testing
call puts

.end: ret

theloop:

ld bc, starttext
call puts
ld a, (loopvar)

.redloop:

sub a, 1
jp z, .end
ld (loopvar), a
ld bc, redtext
call puts
ld a, red
; load red-blue info ($07, just red) and then green info ($00, no green) into port 2
out (2), a
ld a, nogreen
out (2), a
ld a, (loopvar)
jp .greenloop

.greenloop:

sub a, 1
jp z, .end
ld (loopvar),a
ld bc, greentext
call puts
ld a, noblue
; load red-blue info ($00, no color) and then green info ($07, green) into port 2
out (2), a
ld a, green
out (2), a
ld a, (loopvar)
jp .redloop

.end: ret


puts:

ld a, (bc)
cp 0
ret z
call $a2
inc bc
jp puts
.end: ret

eof:


If someone can please help me with either of these, I'll love them forever.


Thanks,
wur

ell, all the OUT (n) has value 1 or 2

VDP is at $98 and $99 (the more commons)
and $9A $9B for msx2 extensions

So

OUT ($98), a
IN a, ($98)
OUT ($99), a

are the more common IN/OUT for VDP

ah, okay. The VDP's 0th port is $98 in the MSX's memory, and its 1 port is $99 in the memory? That was what confused me.

Yes

thank you! Green text on red background never looked so beautiful. ^_^

I am glad that you are using tniASM... ... because this is the compiler used in all MNBIOS's docs. So go and get experience using that.

You might consider disabling the interrupts before messing with the VDP
and enabling them later. Otherwise you're bound to have problems later on ...

Disabling Interrupts: "DI"... and "EI" enables them again (don't forget ;-)

tnAsm == simple in usage with not to much diffecult pre-processor commands etc. so lets you concentrate on youre code!

And there's nothing wrong with that!

--jups even an c#.net and vb.net programmer likes tniAsm !!!---