Re: CBM720 heads up

I am working on connecting to the Internet via a Raspberry Pi (on an Apple /// at the 
moment, partially garbled text).  

Next I plan to work on the B-128 I will let you know if I can locate and use a terminal 
program successfully and post on my site in D0 format.  It's hard to find a good terminal
program that has flexibility to handle the characters generated by mutt.  I am working
on a general purpose .muttrc file.  Still work to do!
Bill

On Thu, Jan 01, 2015 at 11:35:31PM +0100, A. Fachat wrote:
> 
> Hi there, some update and a question...
> 
> I've replaced three dRAM chips, and the CIA used for the IEEE488 and now the 
> machine is working (even SID works). I'll update the pictures on Flickr when I 
> have more time.
> 
> However, I'm looking for a working program to test the RS232 interface. I 
> found the (two) CBM TERM program(s) - but unfortunately I have no idea how 
> they work.
> 
> Has anyone some more information on these terminal programs (e.g. how to 
> change baud rate etc), or another, more simple, terminal program for the 
> 600/700 machines?
> 
> Many thanks
> André
> 
> On Sunday 23 November 2014 18:21:42 you wrote:
> > Hi there,
> > 
> > On Sunday 02 November 2014 02:03:55 you wrote:
> > > > Unfortunately IEEE488 does not work (at least with my Arduino XD2031
> > > > setup... which probably doesn't mean much)
> > > 
> > > Check the CIA and TPI chips then.
> > 
> > Unfortunately I found that it didn't even get to using the IEEE bus because
> > of memory problems.
> > 
> > It looked as if in Bank 1 Bit D5 would be flakey. Writing various patterns
> > to it suggested that when you write a 0 to it, it would not be stable.
> > Address patterns are located in various 256 byte pages of bank 1, but there
> > in the top areas under addresses 127 and 255 of each page.
> > 
> > Unfortunately replacing the corresponding memory chip did not help - same
> > error pattern with a new chip.
> > 
> > So what do you think it could be?
> > - "bank 1" is NOT what uses "/CASSEG1,RASSEG1" in the schematics? then I
> > have replaced the wrong chip (from the wrong bank)
> > - I think the data bus buffer U33 is highly unlikely. It buffers all DRAM
> > accesses and the error is specifically located
> > - One of the four 4-to-1 selectors U27,U28,U34,U35? Bit patterns of the
> > error would then suggest multiple of those
> > - MUX decoding for those selectors? would that not influence all addresses?
> > - Or the PLA U75 in the end which is supposedly known to fail? It creates
> > /CASSEG1,/RASSEG1. But why then only some of the addresses within the bank?
> > 
> > I'm baffled.
> > 
> > https://www.flickr.com/photos/afachat/sets/72157647798386959/
> > 
> > (see also
> > http://www.vintage-computer.com/vcforum/showthread.php?45083-Commodore-B720
> > -repair )
> > 
> > Any help appreciated!
> > André
> > 
> > 
> >        Message was sent through the cbm-hackers mailing list
> 
> 
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