Considering buying ModelSim or Aldec-ActiveHDL/Riviera for PC
Tom Torfs
We are currently running our VHDL simulations with ModelSim on a HP-UX
system. The problem with that is that because the resources are shared
between all the users, things tend to get kind of slow. Also,
ModelSim's user interface likes to crash rather often.
Because of that, and with the cheap and powerful desktop PCs available
today, we are looking at the possibility of buying a PC-based VHDL
simulator (which also supports Verilog and EDIF).
The obvious option would be to go for the PC version of ModelSim,
since that is what we are currently using on Unix. However, several
people here seem to be recommending Aldec Active-HDL as an
alternative. I have a few questions:
1) The Aldec Active-HDL product is marketed as an "FPGA verification
tool". However, besides FPGAs we also target ASIC. Aldec offers their
Riviera tool for that. From their comparison table between the two
products I don't really see a reason why we would necessarily need the
Riviera tool. As long as it can simulate VHDL and a back-annotated
netlist it should be fine. Am I wrong here?
2) What sort of PC platform is needed to run these tools comfortably?
Would something like a 1000Mhz PC running Windows 2000 with 512MB-1GB
of RAM be OK? Is your general impression that the simulations run
faster or slower on the PC platform than on a shared Unix platform?
(qualitatively of course, as there are a lot of variables)
3) Do you have a rough estimate on the cost for this software? About
3..4 people would be using this (not all at the same time) so
something like 2..3 floating licenses would seem a nice solution. For
starters we would probably begin with a single license and see if
things work out. We would still have access to ModelSim on HP-UX as
well, so we can always fall back to that if there are problems.
4) Any other remarks on either ModelSim or Aldec Active-HDL/Riviera
for the Windows platform? We often need to simulate rather large
designs and this for several 100 ms, so speed and stability are very
important. For synthesis we use LeonardoSpectrum (for FPGA) and
Synopsys Design Compiler (for ASIC).
Thanks for your input! I just like to get a general impression of
these products before contacting the distributors for more details.
greetings,
Tom
Paul Baxter
> tool". However, besides FPGAs we also target ASIC. Aldec offers their
> Riviera tool for that. From their comparison table between the two
> products I don't really see a reason why we would necessarily need the
> Riviera tool. As long as it can simulate VHDL and a back-annotated
> netlist it should be fine. Am I wrong here?
>
> 2) What sort of PC platform is needed to run these tools comfortably?
I've been impressed with ActiveHDL on the PC in comparison with Modelsim. To
be fair I've used the ModelSim Altera edition and didn't care for its
interface so was able to move onto AHDL.
Speed did not enter into the comparison at that point. I did however
benchmark a couple of designs and had typical simulation speeds in AHDL
being four times the modelsim AE speed. These tests were with relatively
counter-heavy designs with little combination logic or convoluted data
paths.
Since ModelSim AE is advertised as deliberately being crippled to 25 % of
their top of the range simulator and 50% of their middle range offering, my
very vague impresion was that AHDL is on a par with the top of the range
Modelsim version and of a similar retail price. Not having used the Modelsim
package I can't comment further.
I have discovered from my own experience and those of others in the
newsgroups that the price of both ModelSim and ActiveHDL is shall we say
flexible particularly when they are introducing new users. You can also get
free 10-20 day trials. It is well worth talking to your local distributor.
I do not live and breathe FPGA design all day every day and every year,
because of this I prefer the much friendlier interface ActiveHDL provides
even when it is coupled with a simulator comparable to ModelSims.
A 1GHz Athlon with 512 MBytes is probably a good baseline minimum, though
for larger devices (say 1million+ gates) or larger simulations 1 or more
gigabytes is useful. To be honest, you'll need a machine with lots of memory
and a large screen for either product. Even todays budget models feature
1.5GHz + processors.
AHDL has the option of floating licenses, but it also has the possibility of
a parallel port dongle which can be moved relatively easily to places
outside the netwrk (say to a customers site) when you're debugging. A
printer switch box locally will often save any inconvenience when switching
user machine. I expect Modelsim can offer similar, but this flexible choice
rather than tied to one NIC or similar PC-specific Id suits my way of
working.
AHDL is stable on my machine with APEX20KE designs on three 600KE designs
with no random disappearing segments of system memory or memory usage
creepage (hi Altera, your ears must be burning).
AHDL partially sells itself as a complete solution, integrating multi-vendor
flows, but whilst Leonardo/Quartus PAR does work, it does suffer from a few
deficiencies and inability to tailor the nitty-gritty constraints or
optimisations of your design. I typically use Leonardo to do an initial
synthesis and then use its TCL script run from within AHDL (minor change to
some AHDL script code needed at present to achieve this but relatively easy
to do). Using the AHDL multi-vendor flow directly results in problems if you
use VHDL generics and results in less optimised settings than available with
Leonardo directly
AHDL does well integrating file/project/directory structure with
functional/post-synthesis and timing simulations and also provides several
methods of design entry.
I find it useful to have the block diagram, VHDL wizard and state machine
entry right there in AHDL, but to be honest these tools are just a nice
addition to the simulator rather than an essential integrated must-have
(since Xilinx and Altera provide similar free tools - albeit the AHDL ones
do have a slight edge).
Overall, you won't be disappointed with AHDL, but the main package of the
industry is still Modelsim due to its long history not because it is the
best package on merit now.
Paul
> for the Windows platform?> Tom
Duane Clark
> Hello All,
>
> We are currently running our VHDL simulations with ModelSim on a HP-UX
> system. The problem with that is that because the resources are shared
> between all the users, things tend to get kind of slow. Also,
> ModelSim's user interface likes to crash rather often.
>
> Because of that, and with the cheap and powerful desktop PCs available
> today, we are looking at the possibility of buying a PC-based VHDL
> simulator (which also supports Verilog and EDIF).
>
> The obvious option would be to go for the PC version of ModelSim,
> since that is what we are currently using on Unix.
Or the Linux version of Modelsim. Since your users are accustomed to
Unix, I would think they would much prefer Linux. One of the reasons I
tried Linux, was that I could not bear the thought of coding VHDL
without nedit :-) Not to mention, I was just plain comfortable with HPUX
and Solaris.
And if you already have Modelsim floating licenses, you should be able
to just download the Linux version of Modelsim and start using it.
--
My real email is akamail.com@dclark (or something like that).
Jerry
> Hello All,
...
> Because of that, and with the cheap and powerful desktop PCs available
> today, we are looking at the possibility of buying a PC-based VHDL
> simulator (which also supports Verilog and EDIF).
Abstracting from all personal preferences, some differences in benchmarks,
etc. please remember that YOU CANNOT BUY MODELSIM SIMULATORS.
You are only leasing the license for one year - if you decide not to renew
the contract for another year, say goodbye to your simulator.
MTI/Mentor is one of the few companies that screw up their customers
in that simple and efficient way.
Just evaluate both if you are not sure and consider all your personal
(or your company's) preferences. As I'm always telling my students
during trainings, the only really important factor while choosing
simulator is its level of compliance with the standard. Everything
else (speed, user interface, price, licensing, etc.) is secondary
and if simulator A is 'the best' for somebody, it does not mean that
simulator B cannot be better for you. Somebody else's opinion can be
helpful, but cannot be decisive factor.
Jerry.
Ray Andraka
two because it has an easier user interface, the editor is good, and is
right there in the product. Modelsim is more of an industry standard,
although at this point I think that is only because it has more tenure.
At one point, Aldec's coverage of VHDL93 had some holes, but they were
extremely responsive in fixing those, often with a patch by the end of the
next working day. All in all, I Aldec gives you more for your money: it
has the simulator, but also includes a 1st class editor, dual language
support, probably the best VHDL tutorials out there, state machine and
graphical editors, code coverage tools, an IP core generator and more.
I do maintain the modelsim for customers who are also using modelsim, and
it is useful if I am running a long sim and want to work on source for
another project at the same time. If I had to pick one though, it would
be Aldec, hands down.
Tom Torfs wrote:
> Hello All,
>
> We are currently running our VHDL simulations with ModelSim on a HP-UX
> system. The problem with that is that because the resources are shared
> between all the users, things tend to get kind of slow. Also,
> ModelSim's user interface likes to crash rather often.
>
> Because of that, and with the cheap and powerful desktop PCs available
> today, we are looking at the possibility of buying a PC-based VHDL
> simulator (which also supports Verilog and EDIF).
>
> The obvious option would be to go for the PC version of ModelSim,
> since that is what we are currently using on Unix. However, several
> people here seem to be recommending Aldec Active-HDL as an
> alternative. I have a few questions:
>
> 1) The Aldec Active-HDL product is marketed as an "FPGA verification
> tool". However, besides FPGAs we also target ASIC. Aldec offers their
> Riviera tool for that. From their comparison table between the two
> products I don't really see a reason why we would necessarily need the
> Riviera tool. As long as it can simulate VHDL and a back-annotated
> netlist it should be fine. Am I wrong here?
We don't do much with ASICs, but I do believe you are correct. Aldec does
have features that are FPGA specific such as the IP generator and an
accelerator for FPGA simulation primitives.
>
>
> 2) What sort of PC platform is needed to run these tools comfortably?
> Would something like a 1000Mhz PC running Windows 2000 with 512MB-1GB
> of RAM be OK? Is your general impression that the simulations run
> faster or slower on the PC platform than on a shared Unix platform?
> (qualitatively of course, as there are a lot of variables)
>
Memory is king. I'm using a dual PIII-800 with 2GB and am happy with it
for day-in and day-out use (My business is strictly FPGA design for DSP
applications)
>
> 3) Do you have a rough estimate on the cost for this software? About
> 3..4 people would be using this (not all at the same time) so
> something like 2..3 floating licenses would seem a nice solution. For
> starters we would probably begin with a single license and see if
> things work out. We would still have access to ModelSim on HP-UX as
> well, so we can always fall back to that if there are problems.
You'll want to contact the vendors for pricing. The pricing is generally
at least a little flexible if you have something to offer.
>
>
> 4) Any other remarks on either ModelSim or Aldec Active-HDL/Riviera
> for the Windows platform? We often need to simulate rather large
> designs and this for several 100 ms, so speed and stability are very
> important. For synthesis we use LeonardoSpectrum (for FPGA) and
> Synopsys Design Compiler (for ASIC).
Speeds are pretty comparable. Some designs run faster under Aldec, some
run faster under modelsim. I am using both under NT, and a couple of my
employees are using one or the other under win2000 pro with no stability
problems on either.
>
>
> Thanks for your input! I just like to get a general impression of
> these products before contacting the distributors for more details.
>
> greetings,
> Tom
--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email r...@andraka.com
http://www.andraka.com
"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759
Tom Torfs
Thanks for your remarks. It seems that functionally there are no
fundamental reasons to choose one over the other (bells and whistles
such as included text editor or VHDL tutorials etc. don't really
matter). So our choice will mainly depend on the licensing
conditions/prices. It's possible that after consideration we just
decide to upgrade the Unix machine instead and stay on HP-UX. Again,
thanks for your valuable input.
greetings,
Tom
Mike Treseler
Jerry wrote:
> Abstracting from all personal preferences, some differences in benchmarks,
> etc. please remember that YOU CANNOT BUY MODELSIM SIMULATORS.
> You are only leasing the license for one year - if you decide not to renew
> the contract for another year, say goodbye to your simulator.
It's been my experience that the version you bought will always work.
It's the versions that come out after you quit paying that don't.
-- Mike Treseler
Ian Smith
switched to Aldec/Synplicity. I have to say the latter combination was
cheaper, easier to use and the simulation speeds 30% faster for a 30
minute simulation. Yes ModelSim offers more, but is it worth it in
most cases?
Of more interest to you may be Synplify ASIC. We used both FPGA and
ASIC versions of Synplify WITH THE SAME VHDL code (just substituting
things like RAMs and adding test features). THIS WAS FANTASTICALLY
EASY and saved many hours of frustration with Synopsys, which is not
user friendly at all. The SYNTHESIS TIMES were blindingly fast too.
We used Windows 2000, 1.4GHz Athlon processors and 1GB RAM for 500k
gate designs, which was a reliable platform.
Hope this helps.