Econet
Interfaces
About Econet Interfaces
To be able to use an Econet network, BBC computers must be fitted with an Econet interface. The main component is the Motorola 68B54 Advanced Data Link Controller which governs all the transmission of data on the network as well as detecting the clock signal.
For the BBC Models A, B and B+, the Econet interface is a hardware upgrade to the main circuit board. In the Master Series and many of the later Acorn 32-bit computers, it comes as a ready-made plug-in module.
Acorn System Econet Interface
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This is the original Econet interface, brought out for the Acorn System range of computers in about 1980. It plugs into a System rack and looks surprising similar to the "podules" which would become a feature of the later 32-bit Acorns. Please click on the picture to learn more about the System Econet card. |
Acorn Atom Econet Interface
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When the Atom was introduced, a new Econet interface was needed and this long strip was designed to be fitted inside the Atom case. Please click on the picture to learn more about the Atom Econet card. |
BBC Model B Econet Interface
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The Econet interface in the BBC Model A and BBC Model B is a hardware upgrade. This involves soldering on IC sockets, resistors, capacitors, a DIN socket, a resistor network pack and a set of links to the top left-hand corner of the motherboard. A set of microchips are then added to the modified board. This is a picture of Station 128's insides showing the approximate location of the Econet upgrade on an issue 4 machine. Please click on the picture to learn more about the Econet interface in different issues of the BBC Motherboard. |
BBC Model B+ Econet Interface
 | With the redesigned Model B+ came a redesigned Econet interface. This was again a hardware modification to the B+ PCB with the same basic components, in a different location on the board. Please click on the image to the left to learn more. |
Acorn Electron Econet Interface
I do not know if there was ever an Econet module designed for the Electron. It would be slightly anomalous if there was not, given that the Electron was such a major addition to the Acorn range of computers, although since it was designed as a computer for home use, perhaps it was decided that connection to an Econet was unlikely.
Acorn Econet Bridge Econet Interface
 | An Econet bridge is a bridge between two networks and as such it has one Econet interface for each of the networks it bridges. The Acorn Econet Bridge also has a 6502 processor and 8K of RAM for buffering. Click on the picture link to the left to learn more about the Acorn Econet Bridge. |
Master Series Econet Prototype
 | Clearly Acorn had gathered that the Econet interface was a nuisance to fit when it came to designing the BBC Master. This is a picture of the prototype plug-in modules which they designed and used in the development of the Master. I am the proud owner of these very special items and I hope you will click the picture to learn more. |
Early Master Series Econet Interface
 | This was the first plug-in Econet Module, introduced in 1986 for the BBC Master Series. It followed the lines of the prototype module except that the DIN socket was provided as standard in the Master and not on the board. This early version continued with the policy of not providing hardware collision detect. Please click on the image to the left to learn more. |
Later Master Series Econet Module Issue 1
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With the later Master Series module, collision detect was back and every bit of space on the module was employed to house all the components. The pictures above are of the Issue 1 type, which seem to be just as common (and identical) to the issue 2 ones.
Later Master Series Econet Module Issue 2
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These are pictures of an issue 2 Econet module. For the issue two, the collision detect circuitry was apparently reintroduced. This type of Econet module was used for some considerable time by Acorn. It can be used in the Master Series, Acorn FileStores and many of the 32-bit machines where space permits.
PC Econet Interface
 | The all-encompassing networking system that was Econet even spread to IBM PC compatibles! I am not sure how widely used this became but I hope you will click on the picture link to learn more. |
SJ Research File Server Econet Interface
 | The SJ Research MDFS runs off a Z80-based system and contains the only Econet interface not based around the 68B54 controller. Please click on the picture link to learn more. |
SJ Research Econet Bridge Econet Interface
 | Like the earlier Acorn Bridge, the SJ Research version has two Econet interfaces. These are based on the 68B54 chip, departing from SJ Research's norm of using the Z80 family of chips. The SJ Bridge is run by a 6502 processor. This Bridge was a joint venture by Acorn and SJ Research, so who outvoted whom? Click on the link to the left to learn more about the SJ Research Econet Bridge. |
32-bit Econet Module
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The 32-bit version of the Econet module is slightly smaller than the earlier Master Series version. The connecting pins are much shorter allowing the module to sit much nearer to the motherboard than the 8-bit version.
With the exception of the 68B54, all the components have been replaced with surface mount components.
There are gaps on the board again suggesting the option of introducing clock circuitry.
This type was introduced originally for the A3020 and A4000 machines which had limited space inside them and would not accommodate a podule expansion if the older Master Series type is used.
Above you can see a picture of two different coloured 32-bit Econet modules. It looks as if the gold/brown coloured one was earlier if you look at the serial number but apart from the colour there is no difference between the two.
Although this type was made for the 32-bit machines, I can confirm that it works perfectly on the BBC Master. I have tested one of these extensively inside Station 1 without any problems at all. You can't use the Master Series mounting pegs as they are too tall but apart from this there is no difficulty. This type could be used, for example, in applications where you want to use a ROM expansion board which would get in the way of the Econet module. In the past I have had to build up expansion boards using extra 28-pin ROM sockets to clear the Econet module. This way is much easier.
There is more about the original A3020/A4000 Econet upgrade kit here.
Acorn A4 Econet Module
The Acorn A4 has its own special type of Econet module which is mounted on the underside of the expansion panel on the front. There is more about this module here.
HCCS Econet Interface
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As far as I know, this is the only third party Econet module made for the 8-bit machines. The principal difference is that the components are all on the underside of the module. The circuitry appears to be very similar to the Acorn type although it looks as if the 68B54 is made by ST Micro and not Motorola.
These pictures have been kindly provided by Matthew Cook as I don't own an HCCS module.
InterClock Econet Interface
 | The Interclock module, as the name suggests, is a combined Econet interface and optional clock circuit. Please click on the picture link left to learn more. |
RISC PC Econet Interface
 | The RISC-PC can support Econet and it has its own Econet module. Please click on the link to the left to learn more. |
BeebMaster Econet Module
 | Just when I thought I had catalogued all the different Econet interfaces, I went and had my own version made! The BeebMaster Econet Module is fully compatible with the earlier Acorn Master series version. If you can't find an Econet module anywhere, then you can buy them from here. |
I believe the above list to be a comprehensive guide to all the Econet interfaces ever issued. If you know otherwise, tell me!