New Econet device

discuss both original and modern hardware for the bbc micro/electron
awilliams
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Re: New Econet device

Post by awilliams »

I have exactly the same ADF10 as Phil shows. The part numbers are quite different between the one with the collision detect and the one without even though they both have ADF10 part numbers.
0243,020 iss2 (no collision detection)
0259,200 A iss 1 (with collision detection) 8709 in the top copper layer.
0259,200 A iss 2 (with collision detection) Date on the board removed.
With casual inspection the only difference between the last two is that the copper pour areas on the top and bottom were better connected around the south end mounting hole on the earlier board.

There were at least three different local clones of the non collision detection board. This must have been an up marked one as its got a solder mask. The very large majority of them didn't.
BBCmicroSuppliesEconet.png
BMS-102 identifies it as being from BBC Micro Supplies. Who were in Adelaide.
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arg
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Re: New Econet device

Post by arg »

Bridges do have some kind of backoff behaviour but the code is somewhat opaque (even though I have the source!) and I couldn't immediately see what it was trying to do. At some point I'll work it out and document it - at the time I was concentrating on documenting the network discovery protocol.

Original bridges have no collision detect and so can't tell the difference between collision and 'not listening', and nor can the original transmitting station (which will therefore do the CA delay, but starting rather later than those actually involved in the collision.

A bridge with CD _could_ retry the operation without telling the original station (ie. keep the other side network claimed while it does so), but this is relatively tricky as it would need to be ready to 'abandon ship' if some other station wins the arbitration and wants to transmit in the other direction across the bridge. Also of limited merit in a busy network situation, as what typically happens is that stations A and B collide and then while they are backing off some third station C nips in and finds the line clear - so neither of the originals actually wins. Anyhow, I'm fairly sure current bridge code doesn't do this even on the SJ bridges.
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arg
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Re: New Econet device

Post by arg »

awilliams wrote:
Thu Jun 10, 2021 1:49 pm
0243,020 iss2 (no collision detection)
0259,200 A iss 1 (with collision detection) 8709 in the top copper layer.
0259,200 A iss 2 (with collision detection) Date on the board removed.
So the timeline here:

Beebmaster's prototype boards have newest chip with datecode 8340. It's plausible that this was Brian Robertson's first prototype of this stuff sometime early 1984 when the first Master prototypes were probably in existance.

The Bridge I believe was released sometime in 1984, though I don't have a hard date on this. It was certainly in general circulation by 1985.

B+ was mid 1985, but it was rushed out to cover for delays in the Master and was closely modelled on the B rather than picking up many of the Master changes - certainly the Econet circuit was unchanged from the B. And it was launched as having disc as standard - unclear how many (if any) had factory-fitted Econet, and of those upgraded by dealers/users how many used the existing 'B' upgrade kit or followed instructions in the

Master then launched early 1986. I think at least some 0243,020 iss1 Econet modules were built with the 26LS34, though I'm not certain. Phil's iss2 has an 8612 datcode linedriver chip on it (could have been changed, but soldering looks original), so probably mid 1986 manufacture.

Alan's 0259,200A iss 1 with 8709 in the copper sounds plausible as the date for those.

So no-CD was 'in fashion' at Acorn from mid '84 to early '87, but only shipping in volume (in the UK) for about 18 months. Sounds like it carried on much longer in Australia due to the local clones.
awilliams
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Re: New Econet device

Post by awilliams »

jgharston wrote:
Wed Jun 09, 2021 9:24 pm
arg wrote:
Wed Jun 09, 2021 5:11 pm
I have been starting to collect data on this and other dirty secrets of Econet implementation as I come across them; this document is meant to be a manifesto for interoperation of various new stuff: the main part of it isn't written yet, but the annex on BBC implementation contains quite a lot of detail now:

https://docs.google.com/document/d/1Bd1 ... sp=sharing
Some terminology that is useful to keep consistant:
Bridge: joins two similar networks. Econet-to-Econet is a bridge, Ethernet-to-Ethernet is a bridge.
Gateway: joins two dissimilar networks: Econet-to-Ethernet is a gateway.
That looks like a very handy document I had not previous locked at all at how emulation fitted into the picture.

There are a couple more sections I might suggest.
1.Archimedes Econet broadcasts. These differ from BBC Econet broadcasts to avoid having bridges stamp them out for being too long. Used by the Broadcast loader. I could dig for details if necessary.

2. maximum clock speeds for different hardware. you can go a lot faster if you only have Archimedes upwards.

3. IP encapsulation in Econet mostly used by Archimedes
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jgharston
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Re: New Econet device

Post by jgharston »

Some of which is documented here, some of the documentation that.... erm.... fell into my suitcase when I returned from Hong Kong. :lol:

Code: Select all

$ bbcbasic
PDP11 BBC BASIC IV Version 0.36
(C) Copyright J.G.Harston 1989,2005-2020
>_
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arg
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Re: New Econet device

Post by arg »

awilliams wrote:
Fri Jun 11, 2021 12:43 am
There are a couple more sections I might suggest.
1.Archimedes Econet broadcasts. These differ from BBC Econet broadcasts to avoid having bridges stamp them out for being too long. Used by the
Broadcast loader. I could dig for details if necessary.
Ah yes, I knew of these but haven't yet found an actual specification (I did recently find some correspondence talking about fixing the bridge behaviour to not stomp on them). I can probably mine the bridge source code to find out what it now does, but if you've got an actual spec that would be good to find.
2. maximum clock speeds for different hardware. you can go a lot faster if you only have Archimedes upwards.
I hadn't thought of including that, but it's certainly worth mentioning. I've found various different listings while trawling my archives; I'm not sure they are all consistent!
3. IP encapsulation in Econet mostly used by Archimedes
And the similar-but-not-quite-the-same used by BBC emulators on modern hardware. This is the major piece missing from that document (actually, it was going to be the sole subject of the document, but other things seemed useful to add)
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