> On Sep 22, 2023, at 3:59 PM, Martin Bishop via cctalk <cctalk@classiccmp.org>
> wrote:
>
> 100% disagree, Verilog and SV are bad tools - very easy to do a bad job with
> - penknife grade.
>
> Verilog however is very c like in that it is untyped and prone to all the
> consequent tar pits; see above.
>
> VHDL is a good tool which is typed and like the Algol family of languages
> precludes many follies.
> The 2008 flavor, which is where the tools are curently, is not as pedantic as
> the older standards '97 & '83.
I only know VHDL but I had heard that Verilog is C-like, and yes, C offers an
unusually large set of tools to shoot yourself in the foot with. So it
wouldn't surprise me that Verilog does likewise, which certainly means that it
would be the option to avoid.
VHDL is very clearly based on Ada, which like Pascal and ALGOL takes data types
seriously rather than only as suggestions the way C does. I've built some very
large designs with VHDL, but not because I actually wrote that much code -- a
lot is generated code produced from wire lists. But I did write all the models
of all the 6000 modules, which does add up.
Apart from vendor tools for producing bits for particular FPGAs, you can also
find VHDL simulators that just simulate a model but don't deliver it to a
particular chip. I use GHDL, which is part of the GCC toolset. Yes, a VHDL
compiler, interesting. Among other things, it allows you to link bits in other
languages, so I can take device models from the DtCyber emulator and attach
them to a VHDL-modeled I/O channel.
On FPGAs, it's worth checking what the story is for vendor tools. Some devices
and vendors try to suck large sums of money out of you for them; Lattice is an
example. Even for small devices (like the ispLSI2032 I used years ago) that
expense adds up rapidly. I think they have become somewhat more reasonable
now, offering free tools for the smaller devices. I know Xilinx does so, and
"smaller" covers a surprising amount of capacity these days. I'm pretty sure a
PDP-11 model would fit fine in one of those "free tool" devices, though a CDC
6600 probably won't.
paul
