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