CBM-II schematics

Hallo allemaal,


http://www.baltissen.org/temp/CBM-II.zip

The ZIP contains the SCH for the 7x0 and 6x0, the used LBR and a 
text where I started to analyze the schematics. The SCH for the 6x0 
is far from complete. The honest reason: I'm fed up with it. I have 
a family and work as well and I need some time for other things as 
well. 
I first thought that it was just a matter of renaming some ICs using 
the 7x0 as base. But although the paper schematics look the same, I 
very soon found out that not only the names differed but also gates 
and even pins had been swapped! Creating the SCH for the 7x0 was fun 
but this wasn't fun anymore. I'll see that I update at least the 
keyboard and video part.

The creation of the text started fine: the explanation of the 
74LS299/74LS30 combination went fine. But then..... I have no idea 
where to start. I see things, I understand them (more or less) but 
where to start to put it on paper? 
One of you (sorry, I forgot who) already mentioned it, it is a bad 
design. I think it is more a "I want this and let we try this. Oh, 
it works, so keep it" design. 

I'll give it a break for some days and then I hopefully will have a 
fresh look on it.


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Kind regards / Met vriendelijke groet, Ruud Baltissen
www.Baltissen.org