DMA: Difference between revisions
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DMA copy can be done with the [[BIOSF_UPLOAD]] call. To access DMA directly or to use its other features see information on the [[LC8953]]. | DMA copy can be done with the [[BIOSF_UPLOAD]] call. To access DMA directly or to use its other features see information on the [[LC8953]]. | ||
It is possible to copy about | |||
It is possible to copy at about 1.5MiB/s via DMA. | |||
We have found that trying to copy a 256k block of data will result in a system reset (watchdog timeout?). The DMA can copy 128k blocks without reset. It may be possible to get past this limitation using 68k interrupts but its doubtful. It appears while DMA is working the 68k has no access to the bus which limits its usefulness as its possible to copy at about 2MiB/s via 68k ASM using unrolled code 'MOVE.L (A0)+,(A1)+'. If you need fast data block copying keep away from DMA. | |||
[[Category:CD systems]] | [[Category:CD systems]] | ||
Revision as of 21:43, 5 January 2014
DMA copy can be done with the BIOSF_UPLOAD call. To access DMA directly or to use its other features see information on the LC8953.
It is possible to copy at about 1.5MiB/s via DMA.
We have found that trying to copy a 256k block of data will result in a system reset (watchdog timeout?). The DMA can copy 128k blocks without reset. It may be possible to get past this limitation using 68k interrupts but its doubtful. It appears while DMA is working the 68k has no access to the bus which limits its usefulness as its possible to copy at about 2MiB/s via 68k ASM using unrolled code 'MOVE.L (A0)+,(A1)+'. If you need fast data block copying keep away from DMA.