June 12, 2022

FPGA - Pano Logic thin client (Xilinx Spartan 6)

Pano Logic went bankrupt in 2013 This is something that is called a "thin client". Essentially it is an ethernet connected dumb terminal. Amazingly, the Pano Logic was based on an FPGA, hence our interest.

These were once available for $20 or so, but those days are apparently over.

As of June, 2022, I am seeing the G2 on Ebay for $50 or so. The G1 are selling for $30, but you can sometimes buy several in a lot and save money on shipping.

For some time I thought that you absolutely wanted the G2 and not the G1, but now I am not so sure. The G2 does give you a Spartan 6 rather than a Spartan 3 FPGA, and a bigger one, especially if you are lucky enough to get one with the LX150 chip. However the Spartan 3 in the G1 is big for a Spartan 3, and more stuff has been gotten to work with the G1. So make your choice, and study my table below. Also consider that the G1 are cheaper and more available.

There are two versions of the G2. Rev B has the bigger FPGA (LX150), whereas the more common rev C has the still quite big LX100.

The G2 seems to have two USB ports side by side, the original has only one. The G2 is often marked Rev C-03, while the original is marked Rev C-02. The markings mean essentially nothing.

The big tip off is that the G2 has a DVI connector, the G1 has VGA (but beware photos of devices with a VGA to DVI gadget plugged in).

The original model (G1) used a Spartan-3E XC3S1600E and 32M of ram.
The G2 uses a Spartan-6 XC6SLX150 (Rev. B) or Xilinx Spartan-6 XC6SLX100 (Rev. C) and has 128M of ram. It is apparently the luck of the draw whether you get a G2 with a LX100 or a LX150 (unless the Ebay seller has opened the case and taken a look).

The Hacker news article says that the G1 does have most things working (as of 2019) and: 
The benefit of the G1 is that all interfaces are working now, including DRAM, USB, Ethernet.
USB on the G2 is hard. A bunch of people have tried and failed.

Here is a table I threw together to compare various FPGA devices I either have or could have. 

XC3S250E - Spartan 3E 2004   612 clb, 4896 4-lut, 12 bram, 12 mult, 4 dcm, 172 uio
XC3S500E - Spartan 3E 2004  1164 clb, 9312 4-lut, 20 bram, 20 mult, 4 dcm, 323 uio
XC3S1600E  Spartan 3E 2004  3688 clb, 29504 4-lut, 36 bram, 36 mult, 8 dcm, 376 uio

XC6SLX16  - Spartan 6  2009   1139 clb,  9112 6-lut,  32 bram,  544 slicem, 32 dsp, 232 uio
XC6SLX100 - Spartan 6  2009   7911 clb, 63288 6-lut, 268 bram, 3904 slicem, 180 dsp, 480 uio
XC6SLX150 - Spartan 6  2009  11519 clb, 92152 6-lut, 268 bram, 5420 slicem, 180 dsp, 576 uio

XC7Z010  - Zynq-7000  2011  2200 clb, 17600 6-lut, 1500 slicem,  60 bram,  80 dsp, 2 cmt, 100 uio
XC7Z020  - Zynq-7000  2011  6650 clb, 53200 6-lut, 4350 slicem, 140 bram, 220 dsp, 4 cmt, 200 uio
It is clear looking at this that the LX100 is a significantly bigger FPGA that the Artix-7 FPGA included in the Zync XC7Z010. And if you were lucky enough to get a Pano G2 with the LX150 chip, you would have a very big FPGA indeed. Of course all of this is moot unless you have projects that make use of all of that. So far I am only using a fraction of what is in my XC7Z010 and those boards cost only $15 at the time.

To put things in perspective, consider that current production large FPGA devices have on the order of 2 million CLB. Remember that the devices in the above table are circa 2010, over 10 years ago. A record holder as of 2020 or so is their VU19P with 4.1 million CLB.

Feedback? Questions? Drop me a line!

Tom's Computer Info / tom@mmto.org