Paul H. Lee wrote: > I have an Apple SCSI Card, REV 'C' installed in my ][gs with a ROM 01 > motherboard. The machine has a ZipGSX and 6 megs of RAM. What is the > largets SCSI hard disk I can use? I connected a 250Mb hard disk to > the system, and everything works fine; but when I connected a 2Gig > drive, the system did not even see it. You might be running into a limitation of the firmware in the SCSI card, but it is more likely to be some other kind of compatibility issue with that particular drive, or something like the new drive not supplying termination power while the old drive did. The absolute limit for ProDOS-8 with the original Apple SCSI card is 7 partitions of 32 MB each, for a grand total of 224 MB usable space. A larger drive will work, but extra space will be inaccessible. Under GS/OS, there is a theoretical limit of 63 partitions, and you can have a mixture of HFS and ProDOS partitions. HFS partitions can be up to 2 GB (though they have rather a lot of wasted space if larger than 512 MB), ProDOS partitions are limited to 32 MB. In principle, a SCSI card should be able to support 48-bit block numbers (128 EB), which is the limit of the SCSI command set. There may be an implementation limit in the firmware of the Apple II SCSI cards so that they can only handle 32-bit block numbers, which would limit the drive to 2 TB. An artificial limit of 2 GB would mean that it is only using a 22 bit block number, which would be a rather strange limit. (4 GB or 8 GB seems more likely.) -- David Empson dempson@actrix.gen.nz