which software can used to solve k-map?

[Keith Williams]

I wasn't aware that Karnaugh maps could be (systematically) used for more
than 5 variables? Can they be? Back when I was in school we used the
'table method' (I've forgotten the real name) beyond 4.

Quine McClusky?

And 4 is enough to convince people of the value of HDLs, I think!

Four variable minimization with a K-map is trivial.

 

[Jim Thompson]

[snip]

The subset of VHDL used in logic synthesis is pretty easy to learn.

[snip]

Keith, Can you recommend a text/tool for just the logic synthesis?

Thanks!

...Jim Thompson

 

[Keith Williams]

[snip]

The subset of VHDL used in logic synthesis is pretty easy to learn.

[snip]

Keith, Can you recommend a text/tool for just the logic synthesis?

I text I used was "Essential VHDL" by Rajan
(http://www.vahana.com/vhdl.htm).
It's very well organized for the experienced logic designer who wants
to learn VHDL for synthesis. I got my copy "free[*]" from Synplicity
when I was starting out. The language reference of record is "The
Designer's Guide to VHDL", by Ashenden. You really have to know VHDL
to make use of Ashenden though.

For the tools side, I'd likely start with the free Xilinx ISE WebPACK.
Free software wasn't available when I started out ('99ish), so I used
Synplify and Xilinx Alliance. I was quite happy with Synplicity, but I
wasn't paying the bills either.

[*] "free" ended up approaching six figures.

 

[Charles Edmondson]

[snip]

The subset of VHDL used in logic synthesis is pretty easy to learn.

[snip]

Keith, Can you recommend a text/tool for just the logic synthesis?

Thanks!

...Jim Thompson

Hi Jim,
When I was learning, I used a copy of ModelSim from Mentor, but my book
is in a box (I am moving from a cubby to a home office...) so I can't
remember what it was.

NC-SIM from Cadence is very powerful, but has a little learning curve
due to all its options. Too bad PSpiceHDL never came out. It made the
Capture-NCSIM-PSpice integration a thing of beauty (as can always be
said for vaporware!)

 

[Terry Given]

That's a different kind of problem. Getting 8-inputs to _one_ of your
outputs is trivial, minimizing the whole structure is not.

...Jim Thompson

yeah, thats a bit harder, but not as hard as nick suggests: 17 variables
= 131,072 combinations, whereas nick just has to map 256 input states to
256 output states, ie it still looks like 8 variables, done 9 times =
2304 combinations, ie more like 10 variables.

Counds like 9 separate K maps would do, or use a bit of A2 paper and
make each K-map square large enough to stick all 9 variables in, and do
in parallel. Still faster than fucking around trying to find s/w to do
it. And how do you prove the software is right.....

Cheers
Terry

 

[Tim Shoppa]

8 variables are just inputs,my circuit has 8 inputs,and 9 outputs.

256x9 PROM.

Tim.

 

[Joop]

256x9 PROM.

Tim.

Right. When I was a student I had an small PC-XT with only 512K Ram.
What I wanted was to add some memory, which was not supported by the
circuit board. The memory was addressed via a PAL of unknown
contents. Inputs=9, outputs=8.

What I did was wire it to a socket with a 2764 EPROM layout and read
it as if it was an Eprom.

I still have one of my first C programs that neatly spit out the
minimal PAL equations being given the eprom .bin file. The equations
were not hard to understand and to extend for the additional memory.
Worked in 1 go!

However because of lack of code documentation it is not that easy to
understand anymore how I did that ;-)

Joop

 

[Keith Williams]

Right. When I was a student I had an small PC-XT with only 512K Ram.
What I wanted was to add some memory, which was not supported by the
circuit board. The memory was addressed via a PAL of unknown
contents. Inputs=9, outputs=8.

No PAL at all.

What I did was wire it to a socket with a 2764 EPROM layout and read
it as if it was an Eprom.

Too much work. The 5160 (PC/XT) supported 640K on the motherboard.
All that was needed was replace two banks of 64Kx1 DRAMs with 256Kx1
DRAMs add a 74LS139 (IIRC) and a jumper. ...all done.