Hi all!
As I said in another mail, I'm interested on assembler programming on MSX.
I'm started with simple programs for MSX1, and I have a little problem:
I want to write data to the Pattern Table of Screen 2. Doing it from BASIC
with VPOKE and VPEEK works good, but in assembler not. I've write this
little program:
START: EQU &HA000 ; Start address
SCREEN2: EQU &H72 ; SCREEN 2 BIOS routine
VPOKE: EQU &H4D ; VPOKE BIOS routine
PAT2: EQU &H0000 ; SCREEN 2 Pattern Table Address
COL2: EQU &H2000 ; SCREEN 2 Color Table Address
NOM2: EQU &H1800 ; SCREEN 2 Name Table Address
NUMCHAR: EQU 4 ; Number of chars to redefine
ORG START
CALL SCREEN2
LD HL, PAT2
LD B, NUMCHAR*8-1
LD DE, DEFCHAR
LOOP: LD A, (DE)
CALL VPOKE
INC HL
INC DE
DJNZ LOOP
LD A,(DE)
CALL VPOKE
RET
DEFCHAR: DB *** Data of the new chars ***
Its function is to redefine NUMCHAR characters, that is, to write NUMCHAR*8
bytes in the Pattern Table of SCREEN 2.
But... this doesn't work.
What is wrong?
Thanks!
P.S.: Now, I see a possible problem... the VPOKE BIOS routine modifies the
HL register?
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| Toni Burguera Burguera |
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| E-mail : [EMAIL PROTECTED] |
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| 9D - La Novena Dimensio |
| http://www.geocities.com/Area51/Dimension/9812 |
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