6502.org

I'm wondering if anyone knows of a Commodore DOS-compatible file storage device or server software that runs on a (e.g.) Linux PC which uses (and exposes) sectors larger than 256 bytes.

CBM DOS filesystems are limited to 16MB partitions because of the two bytes used for pointers in the filesystem. However, a 512-byte sector size would allow the partition limit to go to 32MB. A 4096-byte sector would, for example, allow a partition to reach 256MB, and so forth.

Yes, I'm aware that other elements of the filesystem would change as well. E.g., side sectors for REL-files would likely have very different layouts, etc., as would the relationships between super-side sector and regular side sectors. But, on the whole, it seems CBM DOS commands are high-enough level that they should be supportive of larger partition sizes. That said, strict CBM DOS-compatibility is not a hard requirement.

I'm just wondering if there are open source projects along this line which I can study.

Thanks.

Commodore 8 bit used 256 byte sectors. The Amiga used 512 byte sectors.

At the relevant time, even a 16MB storage device was out of reach for most people, and making the best use of such a device would have involved partitioning.

I had a 10MB hard drive for my Apple II in the early 80's... It looked like 70 or so floppies to the system! catalog,d1 ... catalog,d70 ...

The first Linux PC hard drive I had in about 93 was 280MB.

My current 6502/816 filing system uses variable block sizes from 64 bytes (ram/nvram) to 512 bytes (SD card) but only currently uses a 16-bit block pointer, so max. 32MB per "volume" - which is currently an MBR partition on the SD card, so 4 partitions of 32MB .. out of an 8GB SD card... It's a bit of a waste, but hey ho... I did consider going to 1024 byte blocks to take the capacity of a volume up to 64MB, but at the end of the day, it's an 8/16 bit micro and I didn't think the storage capacity was worth the extra RAM needed for block buffers.

-Gordon

Sorry, late to this reply, but sd2iec source code converts a FAT16/32 512 byte FS to CBM, and in native mode, allows unlimited sizes of FS to be used. (Direct access commands are still limited to 16MB, tho)

Jim