Assembly information

For creating MSX ROMs you can check asMSX v.0.10.
Get it at http://www.robsy.net/asmsx.htm

For creating a ROM file using asMSX v.0.10 you only need to include the following header to your source code:

.bios ; this defines all MSX1 subroutine names: ENASCR, LDIRVM, GTSTCK, etc.
.page 1 ; set at 4000h. Use .page 2 to start at 8000h
.rom ; defines the output file as a ROM
.start MY_PROGRAM ; defines the boot address for the ROM file

MY_PROGRAM:
; Include here your code

After assembling you will get a corretly sized (8, 16 o 32 KB) ROM file.

The package has got some simple examples. You can also download a full commented opensource game at http://www.robsy.net/progs.htm

At the moment all the documentation and comments are in spanish, but that shouldn't be a problem for you, being brazilian. Anyway, an updated v.0.11 version will be published by the end of this month, with a translated documentation and several other examples and tiny helpful tools (file converters, compressors, examples, etc.)

Another full-source MSX game is coming. And an updated version of the crappy PONG CLASSIC v.0.10 aswell.

Give it a try, Leandro.

I rewrote a hello world that was lying around here somewhere:

; hoi.asm

; bios routine addresses

Init32 equ 7bh
SetWrt equ 53h
ChGet equ 9fh
ChPut equ 0a2h

; rom header

  size 8000h               ; 32KB ROM
  org 4000h                ; ROM starts on address 4000h

  db "AB"
  dw Start                 ; init address
  dw 0,0,0
  dw 0,0,0

Start
  call Init32              ; bios routine to init screen 1
  ld hl,6144               ; put writeaddress in registerpair HL
  call SetWrt              ; set vdp for writing from address in HL
  ld hl,HelloWorldTxt      ; put adress of our string in registerpair HL
  call Print               ; subroutine that prints string to screen
  call ChGet               ; bios routine to read a character from the keyboard
  ret                      ; return to BASIC ROM

Print
  ld a,(hl)                ; put char that HL points to in register A
  or a                     ; A=A OR A, and set flags, like the zeroflag when A=0
  ret z                    ; return if the zeroflag is set
  call ChPut               ; bios routine to output char in A to the screen
  inc hl                   ; increase the stringpointer
  jr Print                 ; jump to start of the routine to print next char

HelloWorldTxt              ; Label for our string
  db "Hello World!",0      ; an array so to say :)

Of course I am using SjASM (like "sjasm -l hoi.asm hoi.rom").
To create ROM files, you could use asMSX, that has even a ROM directive.

By the way,

Can I use C and Assembly in MSX together?

My first compiling error in Assembly...

.bios 
.page 1 
.rom
.start MY_PROGRAM 

MY PROGRAM:
call Init32

At AsMSX, it returns: Sintax error at line 6...

Mea culpa! Now it returns an "undefined identifier" at the "Call Init 32".

.bios 
.page 1 
.rom
.start MY_PROGRAM 

MY_PROGRAM:
call Init 32