Date   : Mon, 07 Sep 2009 09:51:52 +0100
From   : robert@... (Rob)
Subject: RAM disc

OK.  Found it.

The Advanced 1770 DFS by Advanced Computer Products has RAM Disc
functionality!  The commands only seem to work if the current filing
system is itself, hence the *-DISC-DRDRIVE  syntax.

Here's a review that may (or may not) have been written by me in the 1980s.

Rob



>DFSreview


Review:         Advanced 1770 DFS

                by Advanced Computer Products

                Versions for all BBC models with 1770 disc controller

                BBC Master version here.


First impressions count, and, as with all ACP roms, the packaging was
a lot better than some I've met, with the manual easy to use, and
spiral-bound making it easy to lay flat on a desk (or in my case, on
top of the pile of other manuals!)


The manual doesn't have an index, but it does have a comprehensive
contents page.


One uses the DFS as a replacement for the Master 128's DFS. It even
worked, much to my surprise, in my Master ET, which doesn't have any
disc interface! The commands all worked on the built-in Ram disc,
however.


As one might expect, operation is fully Acorn compatable, but with
enhancements. Standard discs can be formatted, but also one can have
large (62 entry) catalogues, double density, and the facility to treat
both sides of the disc (if you have them!) as a single drive. This
gives you up to 640K on one drive! Usefull if you go in for large
files, and don't want the hastle of converting everything to ADFS. The
first 32 files of a large catalogue discs can be read on a standard
acorn DFS, but you risk corrupting the last 31 if you write to the
disc. Double density & both-sides discs cannot.


RAM disc support is provided, which can use any sideways ram in the
system; this includes the Masters 64K, plus any you may have connected
in the cartridge sockets. ACP are promising a 256K cartridge which
will work with this. Gnice! The ram-disc is normally accessed as drive
8, but this can be swapped with any 'real' drive, as most software
won't support this high a drive number. You can specify ram banks to
use, and it will refuse to use any that are curently occupied by an
active rom!


Drives 0-3 are the normal external drives, 4-7 are for the Master's
Internal drives (I had a peek - there's space for another socket
inside the Master for you to connect more drives to!) and 8 is the ram
disc.


Extra commands offer work files - just SAVE"" - ability to specify
however many files you want open - usefull on the Beeb B version to
reduce PAGE - and all the extra commands found in the Master MOS on
the beeb B.


Files are stored with 20 bit addresses - another 2 bits are allocated
to the length of the file, and the disc sector address. This allows
one to use the enormous disc sizes one can get if one uses
double-sided discs and double density.


Overall, this is an excelent package; obviously an much improved Acorn
1770 DFS. The ram-disc facilities are particually usefully, offering a
very fast filing system. (But remember to copy them to floppy before
you switch off!)


Recomended for anyone who has a 1770 disc controller!



On 28/08/2009, Rob <robert@...> wrote:
> On 28/08/2009, Jonathan Graham Harston <jgh@...> wrote:
>>> *-DISC-SRDRIVE 0
>>
>> It's obviously running something from disk due to the -disc-
>> prefixes. If it was running from an actual RAM filing system, the
>> commands would be along the lines of *SRDRIVE, etc. A quick look in
>> http://mdfs.net/roms/Filing/RAM doesn't suggest anything.
>
> Whilst normally I'd agree with you, this re-directs all disc accesses
> to the ram drive - since the app is running from Econet (I found those
> commands in the !Boot) I'm guessing that the app objected to not being
> run without DISC being the current FS, and the -DISC- redirects
> sufficiently changed the current FS while the command was being
> executed..
>
> I've been busy *DUMPing all the ROM images I have on the fileserver,
> but not found anything obvious.  It may have been one I had as a
> physical ROM loaded into the cartridge slot, so I'd better run through
> my collection of those, too, in case I still have it ..
>
> Rob.
>