Still no news to know whether or not the OCM will be produced,
and we dont even have a deadline , maybe the news will come
in 6 months or later ..!!! who knows ...
I found this link , for 59 USD you have a 50 000 gates fpga
with vga ps/2 connectors , 8 MB of DRAM , 128K of flash and
the programing cable :
I'm not sure what the exact relation between this gates and logic elements. But from what I remember, having 50k gates would be much less than 12k LEs.
A cyclone II with 8K LEs is equivalent to a xilinx spartan 3 with 400 000 gates
and a cyclone II with 20k Les is equivalent to a xilinx spartan 3 with 1millions gate .
so a EP1C12 has 600k gates .
The same board with a spartan3 1millions gates cost then 199USD and 149USD for 400k gates,
more or less the same price as OCM with more capacity but no MSX specific connectors...
The 50.000 gate number is more a commercial number to specify how big this device is... It seems that at least Altera has dropped that kind of strategy a few years ago.
Not so long ago, an FPGA contained just flipflops, some configurable logic and programmable interconnection. That is fairly easy to translate in some kind of number-of-gates statement.
But nowadays, an FPGA additionally contain block-RAM, look-up-tables, dedicated multipliers and a few clock tools. Now the number-of-gates calculation is much more dependent on the nature of the design. If you do e.g. video processing which can benefit from block-RAM, then the current FPGA's are very efficient. If you make a CPU, then I can imagine that it efficiency depends on the availabilty of a large number of look-up-tables.
So, the number-of-gates statements are not so clear anymore...
And about the link, please be aware that Altera might give good numbers for themselves. The number of 'equivalent' gates really depends on the application. I am sure you will find comparisons like that on the Xilinx site as well which might contradict with the Altera numbers.
Another thing to keep in mind is the maturity of the VHDL compiler, the ones you get for free like Quartus and WebPack are probably less efficient than for example Leonardo which is the tool we use at work. The compiler has to recognize structures in your code like pipelines, lookup-tables, block-memory, etc. A few years ago you had to instantiate Altera or Xilinx specific blocks to make use of their specific features.
But that is not the reason of this topic and my reply on it.
If you look for a comparable FPGA development board with an FPGA with the same size, the price is the same or more.
There is a Spartan-3 board from Digilent that is much cheaper, but that one comes without video encoder, SDRAM, Flash, MSX connectors. (by the way, that spartan-3 board is a nice board to start with it, I am playing some months with it already and have made a bus-arbiter, something like a VDP and a PAL video encoder which only needs a simple high-speed DAC)
We must not forget that we do not just buy an FPGA with a PCB and some extra components.
The most important part of what we buy is configured into the FPGA : The MSX implementation in VHDL!
Thanks for the write-up, Erik. Doesn't exactly make it easier to understand, but it gives some perspective on how to look at the numbers. And welcome to the forums!
It seems to me that XSA is a daughterboard of the XST-3.0.
The XST-3.0 Board provides additional support circuitry that the XSA Boards can access through their prototyping interfaces.
This circuitry extends the range of applications of the XSA Boards
Features: 20 bit stereo codec: 8 bit video: RS232: Ide interface: Usb 1.1:
10/100 Ethernet.
Custom circuitry can be built in the prototyping area.
Will this be enough to build an MSX(2)??
I think the Spartan II - 50 is rather small to contain the whole MSX or MSX2 package.
The XSA-200 would be a better choise, but it still is not so big. Buying that kind of device is a risk, because if your design will not fit, you have to buy the XSA-3S1000 later on...
This XSA-200 board would already get to a price of $149 and you would need to have the XST-3.0 which is $199 which is more than the OCM but ofcourse gives a lot more peripherals we might need, like that video input. An NMS 8280 in an FPGA ;-)
I sure hope that this OCM will be produced as soon as possible, I cannot wait to implement something like MegaRam for it... (that is one of the easiest to imagine projects I think)
I think the XSA50 can be used standalone as well since it has its own DC input .
It seems to have connector on the bottom to put it as daughter card off an other system, optionally.
About VHDL , I believe it can be available , I took a look on MSX ESE website and I got some VHDL
sources for vdp/scc /psg , z80 is missing.
I dont think the spartan have PLLs inside so it not possible to generate many clock rate unlike cyclone
which has 2 PLLs inside . ( usefull to make a Z80 at 100Mhz ! even if off chip oscillator is only 21Mhz)
@Leo, You'r right, I call the XSA50 a daughterboard, but the XST-3.0 is a extention.
I was a bit sleepy that time i wrote my earlier post.
@Erik, your name sounds familair to me, former P.T.C I guess.
