27 Apr
2013
27 Apr
'13
12:35 p.m.
On 27/04/2013 20:05, David Riley wrote:
On Apr 27, 2013, at 2:02 PM, Dave wrote:
I can't see why the typical user would want
to either. I also noted that
there are some open-source tool chains out there but many still need the
suppliers tool chain to generate the final bitstream. So we have this:-
http://rapidsmith.sourceforge.net/docs.html
& this
https://github.com/Wolfgang-Spraul/fpgatools
which both look interesting. Also this:-
http://lekernel.net/fpga_toolchain_talk.pdf
I assume the tool chain is like the Xilynx one.
So you can see the generated routing on the chip and even edit it if desired. These are
absolutely amazing tools. I am sure its going to take me a long time to get really
up-to-speed on them, but already I can see a huge potential for doing those sort of jobs
where you just need several things to happen at once, or where a Pic or Arduino just
isn't fas enough...
It's quite similar, which makes sense, since they do
almost the same
thing. :-) I've never had cause to manually re-route anything, though,
and I've been at this a while. Programmable logic has HUGE advantages in implementing
any kind of
synthesized hardware like CPUs, VGA controllers, PCI interfaces, etc.
They're really terrible tasks for CPUs; I'm constantly baffled at
projects like the SwinSID, which use the GPIO port on a microcontroller
to implement the 6502 bus interface. Such a waste of cycles, even if
it is interrupt-driven!
But if thats all you know and understand then thats the
only tool you
can use. 12 months ago I would have done those things with a CPU or MSI
logic...
Conversely, though, there are plenty of things that a
CPU is much more
suitable for, specifically most things that are highly sequential. You
wouldn't want to make a web server on an FPGA, for example, because you
would need to make lots of complex state machines that would be really
hard to debug. Fortunately, it's usually pretty easy to just bolt on
a microcontroller (or build one in FPGA logic, because a CPU is really
just a specialized state machine with some logic and registers bolted
on). Both Xilinx and Altera have soft-core CPUs that are free to use
and toolchains for them that aren't COMPLETE nightmares.
I saw those.
- Dave
Lets se how we get on. Like I am sure I keep saying I want to finish my
Software Pegasus emulator before starting on the FPGA version(s). I also
want to tweak Richards IBM1130 emulator....
.. and I don't retire for over a year so I still have to work .....
Dave
G4UGM