] Weren't you Maarten who introduced the ADC issue? Since someone said the
] Turbo R has an interrupt attached to the ADC and the other MSXs have not
] then I made the assumption all MSXs had an undocumented way (port) to read
] an ADC, which I supposed to be part of the cassette control hardware.
Actually, the MSX turbo R does not have an ADC. The MSX turbo R has a DAC and
a comparator to compare the input signal with the DAC output signal. Using
this comparator and the DAC, you can write an ADC routine, which samples one
byte in 8 steps.
Furthermore, the MSX turbo R does not have any interrupt attached to the PCM
circuitry. There are a few counters which you can read to determine when to
sample the next byte but checking these counters must be done in some kind of
busy loop. Or very often in the mainloop of your program like I did in Zone
terra for playing the PCM sound effects.
In addition to those counters, the FSA1GT also has a programmable interrupt
generator. But this interrupt generator is part of the MIDI extensions. Not
part of the PCM hardware. Though, you can use it to sample on the interrupt.
I did that for example in the frequency analyzer. On the ST I record the data
in a busy loop and on the GT in the background using the MIDI programmable
interrupt generator.
]
] So tell me. Which models of MSX have a DOCUMENTED and accessible 8-bit ADC.
According to my knowledge: NONE
You can only find documented 8-bit ADC in special hardware like the music
module and the audio processor.
Kind regards,
Alex Wulms
--
Alex Wulms/XelaSoft - MSX of anders NIX - Linux 4 ever
See my homepage for info on the *** XSA *** format
http://www.inter.nl.net/users/A.P.Wulms
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