HP-IB disc drive emulation program available
ard at p850ug1.demon.co.uk
Thu Dec 17 13:21:19 CST 2009
> On Wed, Dec 16, 2009 at 2:05 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
> > I can;t see why that would be a problem. The HP protocols are all block,
> > not file, baeed (unlike the Commodore drives for the PET). The drive
> > doesn't have any idea what OS is talking to the it, it has no
> > understanding for the directory or the filesystem.
> While Commodore disks do indeed have a firmware "DOS" that handles
> file-level access and formatted directory listings and such, the
> firmware fully supports block-level access by the B-R/B-W (or U1/U2)
> commands. Infocom used that method for their VM implementation for
Sure. And there were also commands (which I have used) to read/write
locations of the interface processor address space (at least on the
IEEE-488 units which have 2 processors in them, one to handle the
interface, the other to handle the disk data).
> their Z-machine (once you used "CBM DOS" to read in a ~700 byte
> bootstrap loader).
> It's a fully-manual scheme - you tell the disk drive to read track X,
> sector Y into a buffer, then issue a Memory-Read command to pull the
> bytes out, or Memory-Write to stuff bytes in, then tell the drive to
> write that buffer back out to wherever on the media you prefer.
My point was that on the HP drives, _all_ you have is the block access.
The HP drives have no internal filesystem (the commodore ones do, but as
you say you don't have to use it).
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