Hi,
Over the weekend I did some experiments with the Y8950 MSX-AUDIO test
register and I wanted to examine the YM2164 sound chip in the SFG-05, but
my routine to access the registers didn't work. Does anyone know what is
wrong with this routine?
YM2164 and the YM2148 MKS that accompanies it are memory-mapped into $3FFx
in slot 3. Hence they occupy the same address range as the BASIC ROM and a
machine code routine is needed to access them.
ORG #9000
IN A, (#A8)
PUSH AF
OR #03
OUT (#A8), A
LD A, <address>
BUSY LD (#3FF0), A
AND #80
JRNZ BUSY
LD A, <data>
LD (#3FF1), A
POP AF
OUT (#A8), A
EI
RET
This routine simply hung, presumably on the loop that waits for the YM2164
status register to return a not busy signal (bit 7 = 0). Any ideas why,
and what I should do differently / add to this?
Richard
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