| From: | Mats-Olov Rustad |
| Date: | 14 May 2000 at 12:52:46 |
| Subject: | Re: max transfer |
On 13-Maj-00 18:05:49 in eGroups - AmigaOS 3.5 did Don Cox write to amigaOS3_5 about [amigaOS3_5] Re: max transfer:
>On 13-May-00, Colin Wenzel wrote:
>"BUT if you are using broken SCSI software or an old controller you may
>have to set MaxTransfer to 64kB or similiar. This is due to the fact
>that _bad_ SCSI controler software blocks the system until the complete
>transfer block has been copied to main RAM. This may prevent IRQs from
>being executed."
>I think he is referring to something like a 2091 without Guru ROM, or
>maybe the Squirrel SCSI.
The Microbotics HardFrame/2000 SCSI host adapter required a MaxTransfer value
of 0x0001FE00. Higher values resulted in an unusable partition. You could
usually get back the majority of files by formatting the partition with the
Format QUICK option and then running the DiskSalv unformat option. This only
worked if you had lowered the MaxTransfer value of the partition before the
salvage attempt. The HardFrame couldn't even boot with a too large MaxTransfer
value. HardFrame also caused loss of received characters in the internal serial
port every time a file was written to a HardFrame controlled hard disk. This
was the main reason for me to change SCSI host adapter to A2091 and then
installing a serial card, a GVP I/O-Extender.
I never had these problems with an A2091 using 6.0, 6.6, 7.0 and Guru
ROM.
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