Legend states that MaxTransfer came about as a way to deal with the DMA
limitations of IDE drives. Yet my new phase5 SCSI IV Kit docfiles say
that SCSI users have to be careful with MaxTransfer too. I don't recall
any of the many other SCSI adapters ever needing MaxTransfer settings.
Why might this be? I work with REMOVABLE MEDIA (Iomega, etc) which means
I need to find a MaxTransfer and Mask that will work on varying Amigas.
Since the RDB contains the Mask and MaxTransfer info, every time a volume
is moved over to a different Amiga, potential problems (even data damage)
can occur. I'm fuming that AmigaOS STILL handles Removeable Media so
It seems flawed to me that Mask info is defined on the media rather than
by inspecting the IO card firmware and/or active memory spaces.
I get the impression from the docfiles that maybe certain SCSI
adapters might require different MaxTransfers? Also MASK can be a big
problem due to different memory regions being available (varying ChipMem
or different kinds of Fast RAM: 16bit vs 32bit) depending on how any one
Amiga is configured. There's 24 bit address space and 32 bit address
space. And different amount of Chip RAM available (sometimes it's
contiguous with Fast, sometimes not), not to mention pseudo-FastRAM that
can reside in ChipMem-address-space.
HELP! I need to set up Mask and MaxTransfer on removable disks (Iomega
mostly) so they can be harmlessly passed around between variably
configured Amigas like:
unit OS SCSI_unit Accel/Expansion RAM Fast/16/32/Chip
----- ---- --------------- ------------------------ -------------
1200 3.0 GVP-m 1291 GVP 1230 TurboII+ 030/50 8MB 32bit
1200 3.0 P5 SCSI IV Kit Phase5 Blizzard 1230-IV 8-128MB 32bit
1200 3.0 SurfSquirrel Assorted Assorted
2000 1.3 GVP HC+8 (2MB) 030 CBM-2630, 1MB Chip 2MB 16bit, 4MB 32bit
2000 2.1 2090A CBM2058 2MB Fast 16bit 2MB 16bit, 512K Chip
2000 2.1 2091 1MB ChipRam Fatter Agnus 2MB 16bit (on 2091)
1000 1.3 2091 with 2MB 2MB 16bit, 512KChip
1000 2.1 2091 with 2MB *InsiderII w/1.5MB Fast* 3.5 Fast, 512K Chip
A500 2.1 GVP A500-HD8+ GVP HD8+ Impact SeriesII 1MB Chip, 4MB Fast
4000 3.0 Zorro DataFlyer 8MB 32bit
A500 1.3 2090A some kind of BaseBoard? 1MB Fast, 1MB Chip
3000 Var* Mostly CBM native Varies*
A universal Mask and MaxTransfer is what I need.
I checked some HiSoft mountlists for Jaz/Zip removeable media and sure
enough, MaxTransfer is set to 0x100000. That's only 1,048,576 bytes,
which sounds weak. Previously, I never put much faith in HiSoft's iomega
savvy since they used keywords like SectorsPerBlock and
SectorSize/BlockSize (which failed on my A2000's ARP and WB2.1 Mount
commands, and also my A1200's 3.0 Mount command). My pal with a
SurfSquirrel had the same problem, so we both had to comment out certain
keywords to get the HiSoft Jaz/Zip mountlists/DosDrivers to work.
But after reading the P5 manual I'm thinking HiSoft was (at least) right
about MaxTransfer. But is this value dependent on the peripheral, or the
adapter card (or can it be both)? How does one find out the particulars?
I'm thinking maybe this is why the GVP 1291 SCSI adapter always screwed up
for my Iomega drives. Maybe my Mask and MaxTransfer were illegal.
As an aside, I'm thinking about finally installing AFS (or maybe I'll
waste some money and forgo it and try PFS), but it uses 1024 bytes per
sector instead of 512, so I don't know how to set the MaxTransfer for such
Thanks for your expert help!