Log#05: A suitable HW platform for CPU design ?

A project log for YASEP News archives

A backup of the blog before the host erases it. A good opportunity to review the development, twists and turns of this ISA !

Yann Guidon / YGDESYann Guidon / YGDES 04/06/2020 at 19:410 Comments

By whygee on Monday 22 September 2008, 10:10 - FPGA

My order to is delivered : I purchased a couple of "FOX VHDL"
boards from

The FoxVHDL board (image courtesy of Acme Systems, Italia)

This small board has all I need, and only that, for YASEP : a A3P250 FPGA, and a couple of 256Kx16 SRAM at 12ns. More informations can be found at and a new version of the board will appear soon ! (without the VGA connector that takes a lot of space) Even at 100 Euros each, with only 1MB of memory, this is an excellent board with a lot of potential !

Only problem : the SRAM has "only" 12ns of access time. YASEP is aimed at 100MHz. So either I run at 64MHz only (too bad) or I find 8ns versions of the SRAM chips. I've spent lots of effort in the 2nd option and it is not fruitful yet. The 12ns parts are so much easier to get !

I could try to play tricks with the pipeline gates (doing "wave pipelining" in the memory chip) but it's very risky. Well, it would be better to make my own board... with those crazy 200MHz synchronous SRAM chips that I also recently found. But that will come later : It's better to use the Fox VHDL boards first, write the VHDL code, and later only make a custom board.

In the mean time, I should get accustomed to the use of my new shiny hot air rework station. BGA chips are soon going to be solderable :-)


That VHDL board is indeed a very nice platform that is featured in later logs. I think I was too focused on the 100MHz target though...

The "FOX VHDL" board is long discontinued but not before I made more orders. It was soon superseded by the Colibri board, without the VGA connector. I think I got some of the last boards in stock, and I think I even have one proto with A3P1000. I still have to use it...

During a "FPGA swap" Denis sent me his FOX board (in exchange for some Xilinx or Altera stuff). So I have the necessary hardware, which later inspired some of my endeavours (such as #HTTaPand #WizYasep)

Rather incredibly, some design documents are still on ACME's site ! I just mirrored some critical PDF that have vanished.