A Cheese Wedge for the BBC Microcomputer was a peripheral in a box with the same profile and styling as the main computer.
The Second Processors connected to Acorn's proprietary and trademarked Tube interface. The terminology of second processor was slightly misleading, since connected and switched on, the system worked on a "master-slave" model, with the processor in the cheese wedge taking control while the 6502 in the "main" computer simply took on responsibility for I/O.
The 6502 Second Processor was clocked at 3 MHz, a full 50% faster than the 6502 inside a BBC Model B, and also had 64kB of RAM, of which 48kB would be free for applications (compared to as little as 8½kB on an unexpanded Model B).
A sophisticated Second Processor sometimes branded as "Acorn Cambridge Co-Processor" with an Acorn logo, and sometimes as "BBC Microcomputer System 32016 Second Processor" along with the BBC Micro's owl logo. The device uses the National Semiconductor 32016 CPU and National Semiconductor 32081 FPU running at 6MHz. It runs the non-graphical Panos operating system. Various programming languages are available including C, FORTRAN, Lisp, and Pascal, in addition to a version of BBC BASIC. The processor comes with 1MB of RAM as standard.
The processor is also inside the Acorn Cambridge Workstation this time using 10MHz parts and 4Mb of RAM, sold as part of the Acorn Business Computer line.
In 2007 a new ARM processor board using an ARM7TDMI processor was designed and sold, without an enclosure but able to fit within the original "cheese wedge" case.
Used to connect two Econet segments together. An Econet Bridge is capable of automatically learning a simple network topology and selectively forwarding packets from one LAN segment to the other using a simple routing table based on the contents of the network byte in the Econet packet.
The Econet Bridge is unique among the cheese wedge expansions, in that it is a stand-alone device that does not require a BBC computer to operate.