Date   : Wed, 17 Nov 2010 15:57:20 +0000
From   : jgh@... (J.G.Harston)
Subject: Beeb Networking - and another thing

Alan Williams wrote:
>> AUND does not implement NetFS. AUND implments Econet.
>> AUND takes Econet packets and passes them over Ethernet. It does not
>> care what is inside them.
>
> Ah ok, I must have a memory fault on that.  Anybody know where it is  I
> can't find any trace at the moment.

Where what is?

> There *are* 32 bit file handling calls, they are functions 38 to 44 in
> awServer and also read_object_info arg 8.

For other people being confused by this discussion, NetFS understands
file sizes at 24-bit values, so the biggest file that can be accessed
is 16M, or the first 16M of an open file. The low level calls used
for OSFILE 5, =PTR, PTR=, =EXT and EXT= pass the size as a 24-bit
value. The client/server can't just pass a 32-bit value instead
because other data tends to be in the passed data block after the
3 bytes making up the 24-bit value.

I'm aware of those calls, and aware that after 20 years of searching I
haven't tracked down any documentation for them - don't suppose you
have a copy? There's no reference to any of them in awServer.

I'm guessing that ObjInfo 8 gives type,load,exec,len32,access,date,owner.
38-44 must include 32-bit versions of ReadInfo(PTR/EXT), WriteInfo(PTR/EXT)
and ReadFree. Everything else is file-size-agnostic.

I didn't mention them to clarify the discussion.

Just because you add that functionality to a server doesn't
automatically make clients use them. Most RISC OS NetFS clients
use the 24-bit calls, and those few RISC OS NetFS clients that use
the 32-bit calls will fall back to using 24-bit calls where needed
or where the server doesn't provide them.

Just because BASIC V has ORIGIN doesn't mean PLOT has been removed.

> I was cursorily involved in the specification of these extensions, my

As cursorily as my involvement in the 8-bit URI specification? :D
(http://mdfs.net/Docs/Comp/BBC/URIFetcher/Dispatch) I think at my
time Acorn UK were trying to forget about Acorn Far East ;( They
did teach me to use "URI" instead of "URL", though ;)

> My comments in awServer read "27/2/93 Started to implement the
> experimental 32 bit stuff for Bruce at acorn" (Cockburn I suspect)
>
> I can't say what other servers may have implemented this, I would expect
> that Level 4 did.  Nor do I know what versions of client these calls

I've dug around extensively in Level4 and couldn't find any evidence
of 32-bit calls, and disassembled NetFS 5.78 (data 1992 being before
you 1993 date).

> The ones on the wire do change with client type.  Archimedes can open
> more files than a BBC as a result.

I've never been able to do that in practice:

FOR A=1 TO 99
   PRINT A,OPENIN"!BOOT"
NEXT

counts up to 5 before giving Too many files open. (5 being 8 minus
the 3 open for CSDm LIB, URD).

>  The server adapts its behaviour
> based on a machine type peek done on your client by the server when you
> login.

Useful that. I gave clients a different startup library and boot file
depending on their MachineType response ;)

-- 
J.G.Harston - jgh@...