Acorn IEEE488 interface

[Jules Richardson]

Tony Duell wrote:
>> I've also got the schematic for the Acorn System IEEE488 card somewhere - it 
>> wouldn't surprise me if the BBC unit is based heavily on this (I don't think I 
> 
> 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'.

Aha. I've dug my unit out - on the back it says "Made in Britain for Acorn 
Computers" - rather than "by Acorn". There's no manufacturer's name written 
inside - but there is an "II" beside the Acorn part number on the PCB.

> 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...

Hmm, I see what you mean. The manual looks very comprehensive with lots of 
examples - but I can't see where it justifies why the addressing is done in 
this way.

>> I *think* Tony Duell (on this list) has one too. Other than that, those are 
> 
> I do. I think I might also have the IEEEFS ROM that goes with it, but I 
> can't promise that.

I certainly don't have one...

> 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.

 From your description, the one that I have certainly does - 9914 IC, 5MHz 
clock, 75160 and 75162 buffers.

I *think* we've got a stack of Electronics and Wireless World issues, so I'll 
have to look for the article...

cheers

Jules