From: Gideon Zweijtzer (gideonz_at_dds.nl)
Date: 2002-06-24 14:36:52
Marko wrote: |Okay, that's just a different way of putting it. But I would expect a |VHDL tool to crash if it was fed 2^20=1048576 lines like that. |Want to give it a try? Well maybe. 65536 lines should be okay - although it would take long. 20-bit is already a lot trickier. I would love to give it a shot for the C-64 PLA and see if the equations are similar to what people on this group have found. |I haven't done any VHDL stuff, and I don't have easy |access to any commercial software, including Microsoft Windows. No access to Microsoft Windows? How odd... |Converting the binary data to your proposed format or to CNF or DNF is |straightforward with a few lines of Perl or C. I agree. |> If you want to improve readability, you can replace the words inputvector |> and outputvector to a set of signal names that are actually used on the |> Commodore board. | |Yes, but labeling doesn't eliminate "don't care" variables or reduce the |number of terms in a CNF or DNF equation, which is (in my opinion) the |main reason of unreadability. In the worst case, each output can be a |function of all 20 inputs (I'm assuming that the C128 PLA has 20 inputs). Of course I am talking here about the *reduced* equations, not the original generated equations. Anyway, if you don't have access to commercial VHDL tools, you could always write a little program that does the logic reduction for you. The algorithm is not that complicated (as long as you don't want to find an optimal use of temporary nodes; i.e. reuse of some partial logic equations. In other words: straight from input to output is relatively simple). My initial reason to comment about this was that -although it's a nice exercise- converting binaries to equations is time consuming and prone to mistakes. Better let a computer do it for you, right? (Maybe I am just too lazy ;) Euuhmm.. something else I was thinking about... Most GAL's/PAL's can read back the AND/OR array in programming mode, as long as the protection fuse has not been blown. Has anyone tried this approach? Gideon Message was sent through the cbm-hackers mailing list
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