On Sat, 13 Oct 2001, Jason Petersen wrote:
> ----- Original Message -----
> From: "William Levak" <wlevak@cyberspace.org>
> To: <cbm-hackers@cling.gu.se>
> Sent: Friday, October 12, 2001 10:10 PM
> Subject: Re: Drive B-A and B-F commands
>
> >
> > This information applies to the 1541 and 1571. The 1581 does not
> > work in the same way. It keeps the entire BAM in memory. When you close
> > the files, the BAM is written to the disk, but the BAM in memory may not
> > be updated unles you remove the disk and reinsert it.
>
> So the I0: (initialize) command does not refresh the BAM in RAM? ;)
I open a file to the command channel and another file for a memory buffer
using the "#" command. When I am finished allocating the blocks, I close
the "#" file. This causes the BAM to be updated on the disk. Apparently,
Commodore never anticipated allocating blocks without their being used for
something.
"I0" and "UI" are essentially resets. They do not necessarily update the
disk, but once the disk is updated, they will cause the updated BAM to be
read back into memory.
The last two tracks changed may not be correct in memory unless the file
is closed and the disk reinitialized.
The 1581 is different in that the entire BAM is kept in memory. It also
has a full track buffer and may not read the BAM from disk if it thinks
the contents of the full track buffer are current. In this case, you have
to remove the disk from the drive in order to force it to read the BAM.
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