[BBC-Micro] Issue 4 will not accept a 1770

Chris Johns chris at lessthan3.org.uk
Fri Jun 5 18:44:11 BST 2009


>  I'm certain the ROM's are fine, as I have a functioning WE 1770 board 
> (the WE is an issue 1) in an Issue 7 B, that's the machine I         
> used to test the newer components in too.

Have you checked the machine is 'seeing' the ROM? Does another ROM work
in that socket? I've had one iss4 machine with very dodgy ROM sockets in
the past.

While 1770DFS doesn't start up if it can't see it's controller, it
wouldn't be too hard to write a bit of BASIC read the first few bytes
from the ROM to check it is actually there.

I'd also check the /CS line on the FDC  is being driven correctly (ie.
the address decoding is working)  tho this really needs a scope.
-- 
Chris Johns <chris at lessthan3.org.uk>




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