On Fri, Mar 29, 2013 at 11:43 AM, Michał Pleban <email@example.com> wrote: > Hello! > > Teddy wrote: > >> I don't understand. It's not a SCSI drive, its a Western Digital MFM drive. > > MFM is the technology used to store data on the physical disk. Typical > are MFM (like PC diskettes) or GCR (like Commodore diskettes). Yes, but in geek jargon shorthand, MFM also is used to refer to the ST506/ST412 interface of a 34-pin digital cable (with select and step/direction signals) and a 20-pin analog cable (with differential analog head read/write signals). > SCSI is the interface which the disk uses to communicate with outside > world. Typical are SCSI or IDE. Now, yes. Back in the 1970s and 80s, drives didn't use command-packet type interfaces. The physical drive in a D9060/D9090 is a TM602S or TM603S with a 34/20 pin ST506/ST412 interface. The main board in the drive is called the "DOS Board" and has the IEEE interface, CBM DOS, and a 50-pin SASI interface. It's the predecessor to SCSI and is largely pre-SCSI-2 compatible. The other part in the drive is a 3rd-party board that has a SASI interface on one end and an ST506 interface on the other end. That one takes the SASI commands and handles things like stepping the heads, selecting the heads and converting packetized commands into serialized head data. It does the actual work of formatting the drive, but under direction of the DOS Board. Since real TM602S and TM603S drives are quite hard to find, most of us have worked with using much more common ST225 and ST251 drives and ignoring 75% of the capacity. CBM DOS could handle a filesystem up to 16MB with 8 bits of track and 8 bits of sector pointers, but AFAIK, nobody is really trying to push the capacities past the original 5/7.5MB. For one thing, there are no partitions or subdirectories, so all your files are in one place. I don't think it would be fun to have hundreds and hundreds of files with no organization. -ethan Message was sent through the cbm-hackers mailing listReceived on 2013-03-29 16:01:11
Archive generated by hypermail 2.2.0.