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Re: Using FPGA to feed 80386
On Thu, 11 Dec 2014 12:24:15 -0800, Rick C. Hodgin wrote:

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You want a level shifter or translator:

<http://www.digikey.com/product-search/en/integrated-circuits-ics/logic-
translators/2556437>

--  

Tim Wescott
Wescott Design Services
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Re: Using FPGA to feed 80386
Antti wrote:
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Nice.

Best regards,
Rick C. Hodgin

Re: Using FPGA to feed 80386
On 2014-12-11 Antti wrote in comp.arch.fpga:
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It indeed is! I started not too long ago on the zynq, using the Avnet
MicroZed. Now have a daul core bare metal app running. I found this blog
very helpful:
http://forums.xilinx.com/t5/Xcell-Daily-Blog/Adam-Taylor-s-MicroZed-Chronicles-Part-61-PicoBlaze-Part-Six/ba-p/551888
(scroll to the bottom of the page for an index of all articles, starting
at the very first steps.

Even if you are not using the MicroZed I think most of it is very useful
for getting familiar with the zynq.

--  
Stef    (remove caps, dashes and .invalid from e-mail address to reply by mail)

mathematician, n.:
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Re: Using FPGA to feed 80386
On 11/12/2014 19:55, Rick C. Hodgin wrote:
Hi Rick,
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Sure, look at the 387 interface. The 386 does all the hard work of  
decoding the effective address and when the data is ready the 387 grabs  
it.

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Have a look at Enterpoint's Craignell module schematics:

http://www.enterpoint.co.uk/component_replacements/craignell.html

Regards,
Hans.
www.ht-lab.com



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Re: Using FPGA to feed 80386
On Thu, 11 Dec 2014 11:55:14 -0800, Rick C. Hodgin wrote:

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Are you doing this to have fun playing with obsolete processors, or do you  
have a job to do?

If it's the former -- have fun.

If it's the latter -- you are aware that there are all sorts of far more  
modern solutions to this general problem than the one you're proposing,  
yes?

--  

Tim Wescott
Wescott Design Services
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Re: Using FPGA to feed 80386
On Thursday, December 11, 2014 5:11:44 PM UTC-5, Tim Wescott wrote:
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It's a mental exercise right now.  I have never considered anything about
hardware in my past.  I'm a software guy, and always thought of hardware
as being outside of my reach.  However, a short time ago I was introduced
to Verilog and the FPGA.  Since then I've had this flood of ideas on how
things might work ... so, I ask questions. :-)

I do have an old 80386-16 MHz ceramic CPU (several actually), along
with 80486 through Pentium various models (some of which are 3.3V),
along with AMD K5, etc.

I was basically just thinking through the process.

Best regards,
Rick C. Hodgin

Re: Using FPGA to feed 80386
On Thu, 11 Dec 2014 14:26:42 -0800, Rick C. Hodgin wrote:

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Hey Rick:

I don't know where a good place to put this is, so I'll put it here.

What you needed to do to answer your question was to look at the data  
sheets for the FPGA and processor in question, and look at the schematic  
of the FPGA test board.

The data sheet for the processor will have four numbers that are pertinent  
to this problem: the input high voltage, the input low voltage, the output  
high voltage, and the output low voltage.

The FPGA data sheet will have those same four numbers, except that FPGAs  
often let you power up different I/O banks with different supplies.  In  
addition (if you can't power up an I/O bank with 5V), the FPGA data sheet  
will tell you if the thing can tolerate voltages higher than the power  
rail.

Leaving the board schematic out of it (because we know there's a gotcha  
there), you match up the input high voltage of a receiving chip with the  
output high voltage of a transmitting chip.  If the latter is greater than  
the former, and the output high voltage isn't greater than the voltage  
that the receiving chip can stand, then that connection is OK.  You need  
to do this for ALL THE PINS ON BOTH CHIPS, although usually those five  
numbers are the same for all pins on their respective chips.

Had you done this, and found it good, you'd still have those diodes on the  
FPGA board (they're protection diodes, to prevent software guys from  
damaging the hardware :) ).

This is just one of the tasks that you need to do any time you're going to  
marry two chips on a board.  It's easier if everything is CMOS and  
operates on the same power rail -- in that case, you're probably OK.  But  
as soon as thing 1 operates at one voltage and thing 2 operates at  
another, you have to dig through all this stuff, and put in level  
translators if the chips themselves aren't up to snuff.

--  

Tim Wescott
Wescott Design Services
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Re: Using FPGA to feed 80386
In researching the 80386 datasheet, I came
across a comment that said a later version of
the 80386 core was completed in "fully static
CMOS," whatever that means, for a couple
devices, as per the wiki:

http://en.m.wikipedia.org/wiki/Intel_80386

Best regards,
Rick C. Hodgin

Re: Using FPGA to feed 80386
On 12/12/2014 7:41 PM, Rick C. Hodgin wrote:
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In early processors from Intel they used dynamic logic which used  
capacitance to store voltages rather than FFs.  This voltage would leak  
away if it was not constantly refreshed, so there was a maximum clock  
period.  That was all about saving space in the chip, but it required  
complicated multi-phase clocks.

As the process geometries got smaller and they could pack more onto the  
chip they started using clocked FFs which have no maximum clock period  
and so are "static".

--  

Rick

Re: Using FPGA to feed 80386
How would I go about making my own boards?
I am aware of commercial companies which
have software you can download, and construct
the layout through their process manufacturing,
and you will receive boards and solder masks.

But are there things you can do yourself? Buy a
blank copper layer, cover with a photoresist,
expose a mask, and then chemically etch away
the exposed or unexposed are (depending on
the resist)?

Best regards,
Rick C. Hodgin

Re: Using FPGA to feed 80386
On 12/14/14, 1:47 PM, Rick C. Hodgin wrote:
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Yes, there are home kits for building boards. Unless you go VERY fancy,  
you will be limited to 2 sided boards, and likely do NOT have plated  
through holes, so you need to solder through jumpers to get from one  
side to the other.

Generally, the line width you can make with this sort of system isn't  
any where near what you can do with commercial fabrication.

If you are only planning a few boards, it may be cheaper to use some of  
the short run prototype shops, as there is a moderate investment in  
tools to be able to make your own boards.

Re: Using FPGA to feed 80386
On 12/14/2014 1:47 PM, Rick C. Hodgin wrote:
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I don't bother with that anymore.  I think I made one or two PCBs back  
in my misspent youth though.  It is a messy, somewhat complex and  
unrewarding task to make crude PCBs yourself and then you have corrosive  
chemicals to dispose of.  Even assembly of PCBs is a PITA in my opinion  
although I will do a little work on them.  But this is my perspective  
where my eyes and hands are nowhere near as good as they used to be even  
if my patience is a lot better.

I much prefer to let contract assembly houses do my dirty work for me.  
PCBs can be downright cheap if you limit them to 4 layers.  There are a  
number of places which will batch numerous user's boards to make panels  
(the size that the PCB fabricator produces) and then ship everyone their  
individual boards.  Oshpark is one I have seen a lot of.  ITEAD provides  
a similar service and will also do the assembly.  Then I just read about  
dirtypcbs.com who also make cheap PCBs.

FPGAs are easy because you can test your code in a simulator and reload  
in the hardware anything that doesn't work.  Actual hardware is not so  
easy and mistakes can get expensive.  You need to start small and work  
your way up.  Laying out a board has a *lot* of pitfalls.  With a $50 to  
$100 worth of parts on the board you don't want to mess it up too many  
times.

--  

Rick

Re: Using FPGA to feed 80386
I found this video. It was interesting. Also some
instructables on the process.

    
http://www.youtube.com/watch?v=tWnfnt2rNO0


Best regards,
Rick C. Hodgin

Re: Using FPGA to feed 80386
Even better:

    
http://m.youtube.com/#/watch?v=4SNkzoOvoD8


Best regards,
Rick C. Hodgin

Re: Using FPGA to feed 80386
On 12/14/2014 7:50 PM, Rick C. Hodgin wrote:
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https://www.youtube.com/watch?v=lxRNQbEGwm4


--  

Rick

Re: Using FPGA to feed 80386
On 15/12/14 00:50, Rick C. Hodgin wrote:
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Using high-power lasers which aren't fully enclosed is a recipe for
blinding an innocent passer-by. Specular reflections can be unexpected
and dangerous.

Saying "oops, sorry" just isn't enough when that happens.

I don't care what someone does to their own eyes. I do care what
they (might) do to other people's eyes.


Re: Using FPGA to feed 80386
Tom Gardener wrote:
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In the first video he held up filter glasses so he has some idea of eye protection.

This looks like a prototype being built in his
basement lab.

Best regards,
Rick C. Hodgin

Re: Using FPGA to feed 80386
On 15/12/14 13:13, Rick C. Hodgin wrote:
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Sure; but I don't care about his eyes.

*Did he also give them to passers by,*
*e.g. everyone else in the building?*

Motto from BT Labs, prominently displayed on relevant walls:
"Do not look into laser with remaining eye".
They were /very/ serious about specular reflections.


Re: Using FPGA to feed 80386
On Monday, December 15, 2014 8:36:34 AM UTC-5, Tom Gardner wrote:
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To me it looks like it's done at his home in his basement.  Perhaps it's
done somewhere else.  Being as it's a prototype, and being particularly
filmed for the video, it makes sense that it's all open.  I'm sure the
final form would offer sufficient protection.

Best regards,
Rick C. Hodgin

Re: Using FPGA to feed 80386
On 15/12/14 13:59, Rick C. Hodgin wrote:
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What makes you think that?

Counterexamples from a 10s google:

https://www.kickstarter.com/projects/1537608281/lazerblade-the-affordable-laser-cutter-engraver
http://mr-beam.org/
https://www.kickstarter.com/projects/820277733/laser-cube
https://www.kickstarter.com/projects/mrbeam/mr-beam-a-portable-laser-cutter-and-engraver-kit
https://www.kickstarter.com/projects/2117384013/flux-all-in-one-3d-printer-unlimited-elegant-simpl

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