Labels:book | bulletin board | earth | reckoner | sky OCR: otherwise it might miss data SCSI-DMA however means the CPU initiates a data transfer and tells the SCSI hardware where to put the data The SCSI hardware then transfers the data and writes it down to RAM into reserved area without interaction of the microprocessor that is free to do something more useful. Unfortunately System Software didn keep pace with hardware improvements: support DMA the os must be aware of a second hardware device (for tech junkies: Bus Master) possibly reading or writing to an area of 'main memory which must not be touched as iong as the DMA transfer is in progress. This conflicts with normal operation of the Macintosh os that simply assumes it has control over all available memory all the time So the new fancy hardware support for real performance improvements buil ...
