Changes

All of the devices on The Music Machine data bus are accessible to the Amstrad within its I/O space. ACIA transactions must use 16-bit IO instructions; the converters are accesible via 8-bit IO instructions.

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| INTERUPT SEL

| Writing 01 to this port disables internal Amstrad interrupts and replaces the IRQ signal from ACIA. Writing 00 restores normality. ''(Unclear how this works exactly - the description sounds as if uses an [[External Interrupt]] (rather than a [[NMI]]), and as if it does somehow disable the CPC's internal 300Hz interrupt?)''

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| ACIA Control

| See [[6850 ACIA chip]] for details

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| ACIA Data write

| See [[6850 ACIA chip]] for details

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| ACIA Status

| See [[6850 ACIA chip]] for details

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| ACIA Data read

| See [[6850 ACIA chip]] for details

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| DAC WRITE

| Data can written to the DAC via this port

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| ADC READ

| The contents of the A-to-D can be read via this port. Note that the A-to-D must have been startet at least 20uS before this port can be read

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| ADC START

| Reading or writing to this port will start analogue to digital conversion

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