On 12/8/09, Didier Derny <email@example.com> wrote: > Hi, > > SASI is really easy to emulate, Abstractly, yes. > SASI is really simple no heads, no tracks, just a continuum of blocks 0 .. > size of the disk > > For the rest it's almost a simple parallel port. Sure... same as SCSI 1 (which isn't much more complicated than SASI). > I'll have to check the firmware of the 9060/9090 to see what command need to > be implemented > (probably 4 or 5) status, inquiry, read, write, format That is where I fell into the "not enough time to follow up" pit. Knowing which commands are created is really the hard part. I don't think SASI supports INQUIRE, which is why there is only a jumper for the number of heads the controller is expecting - the controller has to "know" somehow, and in the case of the D90x0 drives, it's built into the code and into a couple of tables. That jumper is used to choose between two options. I did get that far into the code to see that bit get read. READ and WRITE are going to be straightforward since the drive is so "small" compared to the max drive size (24-bit block address?), but FORMAT is a big question in my mind - what _is_ the DOS card sending to the SASI controller in the D90x0 drive? It should be easy to find in the code, since it's attached to the "(N)ew" code, but to my knowledge there isn't a well-commented disassembly of the DOS board code out there anywhere. Also, that code will be different between Rev A and Rev C ROMs, just so you know (45 minute format vs 2 hours on the same-sized drive). > I'll write a short documentation on SASI. That would be great. There's quite a bit of stuff on ancient SCSI, but not anywhere near as much as documentation on SASI since it wasn't as widely deployed before becoming more standard. -ethan Message was sent through the cbm-hackers mailing listReceived on 2009-12-08 21:00:04
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