Quote:
Originally Posted by Toni Wilen
I assume DMAL is also used for disk dma? I guess disk dma DMAL pulses come before audio? (odd/even for reads and writes?)
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Yes, there are 6 DMAL slots directly preceeding the 8 dedicated for the audio subsystem.
The slots 1, 3 and 5 are active whenever the disk DMA is idle or in write mode.
The slots 2, 4 and 6 signal the need for data transfer.
During writes the slot #2 is active whenever there is at least one empty entry in the FIFO inside the Paula. The slot #4 is active whenever there are at least 2 empty entries and the slot #6 whenever the FIFO is empty.
During reads the slot #6 is active whenever there is at least one word to transfer. The slot #4 whenever there are 2 words to transfer and the slot #2 whenever there are 3 words to transfer. During disk reads the DMA slots are allocated in the reverse order (the first used is the third one). That might be important for cycle exact emulation.