Re: [colorforth] ForthBox and FPGA

[Jecel Assumpcao Jr <jecel@xxxxxxxxxxxxx>]

On Tuesday 02 March 2004 02:34, Samuel A. Falvo II wrote:
> Can you provide some links to said software that can run under Linux,
> even if under Wine?

Here are some instructions for getting it to work with Wine -
http://www.computing.surrey.ac.uk/personal/st/R.Peel/webpack.html

and the software itself -
http://www.xilinx.com/ise/products/webpack_faq.htm

Note that the non free version is supported on Linux, but for WebPack 
you are on your own (with the above instructions). The graphical front 
end for the tools is really nice but only works on Windows.

> Now that is pretty slick.  I hadn't considered that possibility.  I
> would prefer to do simulations, however, at least to get the initial
> design implemented.  Maybe once the chip was actually half-way
> functional, then the "interactive debugging" can be used.

At least for Verilog, there seems to be some very usable free simulation 
tools for Linux. The WebPack does include a restricted version of a 
simulator, but I haven't tried it.

I first tried FPGAs back in 1986 and the Xilinx tools were much more 
like OKAD. You worked with an abstract representation of the physical 
chip and clicked on tiles to reprogram the blocks or change the 
routing. Though it is nice to write a few lines of VHDL and have a demo 
working in a few minutes, for serious work I would prefer the old 
tools. The paid Xilinx tool does include a FPGA Editor, so you could in 
theory still work this way.

> Well, delta-sigma and PWM aren't precisely the same thing.  Though
> they are certainly related technologies, D-S has several advantages
> over PWM, but requires slightly more sophisticated
> algorithms/circuitry (depending on whether a hardware or
> software-based solution is used).

http://direct.xilinx.com/bvdocs/appnotes/xapp154.pdf is what I used for 
the sound. As you said, a PWM converter would just be a counter and 
compare circuit (like in the original Mac).

> I don't much care for supporting USB 2.0.

A guy in Japan attached the connector directly (with some resistors) to 
the FPGA and was able to talk with success to some USB 1 devices. I 
used a Philips PDIUSBP11A chip in the truck terminal project, but the 
version with the package I selected has become hard to find so I plan 
to try the "just FPGA" solution.

http://member.nifty.ne.jp/fpga/freeip/usb/ (in Japanese)

> You seem to be mistaken that I aim to support Chuck Moore's
> ColorForth on this machine.  This is not the case.  Any Forth that
> runs on top of this box will be designed *specifically* for this box,
> from the ground up.

Ok, what will be the advantages of your Forth?

When I started the truck terminal project, I made some simple changes to 
both ColorForth and MISC to support objects. I like for it to be easy 
to have temporary data and also an intermediate context between very 
local (stack) and very global (dictionary). Later my clients complained 
about the syntax so I made more small changes and it became a 
Smalltalk. http://www.merlintec.com:8080/hardware/Oliver shows the 
result, which might seem very different from a regular MISC but really 
isn't.

I have looked around and it seems you can still get some older chips in 
a 84 pin PLCC package for which there is a nice through-hole socket for 
people hand soldering boards. What I said about older chips still 
stands - a Spartan XL XCS10XL-3PC84 costs $20 and is slow and small 
compared to more modern and cheaper alternatives. In fact, it isn't 
easy to find this part in the Xilinx web site.

A similar alternative from QuickLogic is their QL4016 chip for $24. It 
is fuse programmable, so you don't get the advantages of interactive 
development (and we wouldn't be interested in Forth if we didn't care 
for this, right?) that I described in my previous email. On the other 
hand, you don't have to include any programming circuit on your board. 
You can send your design to QuickLogic and they will send you a free 
programmed sample to you by mail. You can also get programmed parts in 
production quantities.

How many parts in all do you think you will need? If the number isn't 
large, then perhaps Dr. Ting's remaining stock of P21s might be an 
interesting solution for this project? The Ultratechnology/Ofette site 
is off the air right now, so I don't know if there are any still 
available. If, on the other hand, you will need 5000 or more then 
cooking up a new batch of F21s could be an alternative. Though since 
Jeff Fox has moved on to better things, I don't know if he would be 
interested in this or if it is even possible. In any case, given that 
you want more than 16 color TV output you would need a little extra 
hardware.

I am not sure if this is too far off topic for this list or if there are 
more people interested in this.

-- Jecel

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