At 9:56 PM -0700 8/1/99, [EMAIL PROTECTED] wrote:
>After re-reading the TOAST manual, I have now learned that the 2400 does
>in fact support SCSI manager 4.3.
>
>I'm afraid that does it for me as far as the 2400 v. 2300 battle is
>concerned. But now the lingering question: why?
>
>What is so different between the 2300 & 2400 that one can use SCSI Manager
>4.3 and the other can't? I always understood the problem with Powerbooks
>and SCSI Manager had to do with the HD-50 connector and inadequate
>internal SCSI bandwidth. Did I have wrong information or has Apple somehow
>found a way around this?
It's a question of whether the motherboard implements DMA (Direct Memory
Access), which allows the SCSI controller to directly read and write
memory. This greatly reduces the load on the CPU and increases speed too.
SCSI Manager 4.3 requires DMA. All the PCI PowerBooks have DMA (2400/3400
onwards), but older models do not.
4.3 may not be an absolute requirement, though: I have heard of success
burning CDs on the 1400 and 5300. Apparently burning at any speed higher
than 2x is likely to fail, but 1x or 2x is OK.
Tim Seufert
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