[2GS] Using SCSI drives

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papapoipoi

New Tinkerer
Nov 2, 2025
3
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Hi all,

I acquired a few month ago an Apple 2GS as I was a big fan of my Apple 2e back in the past…

I wanted to be able to have an « internal » storage with as much as possible space on it which could you used by GS-OS and maybe PRODOS.

Note I already own a Floppy Emu, but I find quite slow and mostly I cannot use it when my 5.25 apple drive is connected.

So, I ordered a Cirtech SCSI card, I received a few days ago, and was trying to use it with a ZuluSCSI Micr-SD card reader.

After several attempts, I managed to have it working but some real limitations :
  • Right now, I only manage to have two disks available in GS-OS. Whenever I try to have more than 2, the one with the 0 id, which contains the system and is supposed to be mounted first, is either not mounted or mounted after some others, which leads to a non bootable situation,
  • I’m not able to manage « big » partitions as I want. Whenever I create an empty visual drive which is more than 32Mo, the disk utility let me format it but won’t let me create partitions on it (button is disabled). Than means that even if I solve my number 1 problem, I will be limited to 7 partitions of 32 Mb.
Any comments, advices, tutorials would be welcomed…

My configuration :
  • Apple 2Gs REV1 with 4mo of RAM,
  • Cirtech card inserted in slot 7, set as « My Card » in GS configuration panel, used in Safe mode (documentation isn’t very clear to if it could work in Fast mode),
  • GS OS 6.04,
Thanks (and sorry for my English)....
 
Last edited:
Retronaut

Retronaut

New Tinkerer
May 11, 2025
23
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I believe (others can correct me) that ProDOS has a hard limit of 32mb per Volume. This may seem crappy by todays standards, or even those of the 90s, but when the first hard disks came out, 5mb and 10mb drives were rocking it. So, I think with your SCSI card, you will be "limited" to only 7 devices with 32MB on each. But if you consider most games take less than 140kb, thats a LOT of software you can fit on those devices.
Beyond this, you COULD get another SCSI card and then mount another 7 drives. Or, maybe a better/cheaper solution is to get a Booti and use that to provide more drives.

As for booting, I have an Apple Fast SCSI card, and it wants its first device to be 6, its possible this was a more general default. So try making a boot drive with ID6 and see if that boots.
 
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papapoipoi

New Tinkerer
Nov 2, 2025
3
0
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Thank you very much for your reply.

I will try the ID6 trick, and will let you know.

My understanding is that PRODOS partitions can not exceed 32MB, but disk drives can be bigger (I managed to see a 200 Mb disk before formatting it, but it won't let me create several partitions on it... so when I format it I only get a 32Mb partition), for a reason I don't really understand.

Best regards...
 
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NJRoadfan

New Tinkerer
Feb 6, 2022
57
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Jumper to fast mode (basically this sets the card to appear as a SmartPort device) and place it in Slot 5 if you want to use more then 2 ProDOS partitions on a drive.

These early cards are very weird about partitions as they tend to be written "raw" without any partition table on the drive. The software included can partition a drive, just don't expect these images to work properly with imaging software, although CiderPress II might be able to handle them. Set the ZuluSCSI to emulate one hard drive at SCSI ID 6 roughly 64MB in size to start. This card appears to only support two "physical" drives connected to it. Its not a full blown SCSI interface like the Apple cards.

The only Apple II SCSI cards that do things the "Apple way" of using the Apple Partition Map is Apple's cards and the RamFAST SCSI card.
 
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