Acorn IEEE488 interface

It might be, it might not. The 'Acorn' IEEE-488 interface for the Beeb doesn't seem to be an Acorn design. The article to find is in 'Electronics and Wireless World' February 1984, pages 24-26 ('IEEE488 interface for the BBC Microcomputer'). It imples the interface was actually designed by a company called 'Intellegent Interfaces'. Anyway, there is a schematic. It's based round a 9914 chip along with the 75160 and 75162 buffers. There's a 5MHz clock circuit, an address decoder, a data bus buffer, and the normal circuit to de-glitch the page select line on the 1MHz bus. That's all. Nothing remotely odd. Link S1 selects system controller mode, link S2 selects active pull-ups on the IEEE488 data lines. The other useful thing in this article is an example program using the IEEEFS filesystem ROM, and a list of the commands you can use with the interface. It appears you open a 'file' called "COMMAND" and another called "DATA", you write command strings to the first one and use the second one to actually transfer data on the bus. Addressing looks totally strange, you seem to open a file with a name correspodning to the device address in decimal and then use the file handle of _that_ file in subsequent comamnds. Hmmm... I do. I think I might also have the IEEEFS ROM that goes with it, but I can't promise that. You;'ve just made me worried. I am going to have to try to find my unit to see if it agrees with the circuit in Wireless World. -tony