Spartan 3E evaluation board manufacturers

"Alessandro" <apoppi@email.it> wrote in message 
news:ga157k$6ck$1@aioe.org...
> Hi!
>
> I'm the designer of this zx-spectrum clone project: 
> www.zxbada.bbk.org/badaloc_fpga
>
> I'm looking for evaluation board or starter kit manufacturers. May 
> somebody provide me with the one from which he/she bought it's board?
>
> I already own the Spartan 3E $149 board from xilinx, but I'm looking for 
> something as close as possible to this configuration:
>
> Spartan 3E 500 in PQ208 package
> Almost any pin available on some kind of strip/connector
> Fast static ram (example 1MB 10ns)
> Spi prom for configuration
> Power supply, xtal osc (50MHz would be perfect)
> rs-232 port
> Vga output

There's this: http://www.knjn.com/board_Xylo.html. Seems way overpriced at 
$300 USD.

Also take a look at Digilent's Nexys2 
http://www.digilentinc.com/Products/Detail.cfm?Prod=NEXYS2&Nav1=Products&Nav2=Programmable. 
$100 USD. Sounds like a good match except the FG320 package, 16 MB SDRAM, 
and Xilinx platform flash. VGA output is 8-bit color only.

Why not go straight for your own protoboard instead? Can't you just simulate 
the SRAM if you're concerned about timing?

Alessandro <apoppi@email.it> wrote:


 >16K rom image from spi flash address $10000 (1MB offset). If a spectrum 16K 
 >rom was programmed there, then you had a VGA-PS/2 keyboard 16K spectrum :-)

No connector for microdrive and the ZX printer? :-)

Did you not think it is more nice to have a ZX in a box like this:

http://www.rose-bopla.com/Prod_Pgs/BAB/Prod_02_Alubos.htm

PS2 Connector and sdcard slot on front, and VGA on back?

Olaf

Olaf Kaluza wrote:

>> 16K rom image from spi flash address $10000 (1MB offset). If a
>> spectrum 16K rom was programmed there, then you had a VGA-PS/2
>> keyboard 16K spectrum :-)
>
> No connector for microdrive and the ZX printer? :-)

:-)

The microdrive requires a dedicated controller, but the zx-printer could be 
driven by just adding an edge connector and bringing Z80 signal there. Btw, 
I've also designed a simple interface for real machines (I mean zx-spectrum) 
which gives sd-card, IF1 (rs-232 and network), kempston joystick, flasorom 
and ram capabilities. www.zxbada.bbk.org/zxmmcp and the simpler 
www.zxbada.bbk.org/zxmmc

> Did you not think it is more nice to have a ZX in a box like this:
>
> http://www.rose-bopla.com/Prod_Pgs/BAB/Prod_02_Alubos.htm

I'll keep it in mind :-)

Ciao!
Alessandro

MikeWhy wrote:

> There's this: http://www.knjn.com/board_Xylo.html. Seems way
> overpriced at $300 USD.

Yes, it's interesting but overpriced, imho.

> Also take a look at Digilent's Nexys2
> http://www.digilentinc.com/Products/Detail.cfm?Prod=NEXYS2&Nav1=Products&Nav2=Programmable.
> $100 USD. Sounds like a good match except the FG320 package, 16 MB
> SDRAM, and Xilinx platform flash. VGA output is 8-bit color only.

I saw this board a couple of weeks ago. Maybe a good choice now that I know 
that sdram is simpler to drive than the ddr. That kind of sdram, 
furthermore, can be accessed a static ram (slow: 70ns).

Do you think that the typical random access of an 8 bit microprocessor could 
take advantage of the "sdram mode" over the 70ns "static ram mode"? I mean, 
an average-design sdram controller could get more out of that chip than 70ns 
in random rd/wr?

> Why not go straight for your own protoboard instead? Can't you just
> simulate the SRAM if you're concerned about timing?

It was just to save time and to make it easier for those interested in 
building one, by providing a source for ready hardware.

Ciao!
Alessandro

Frank Buss wrote:

> Use non-DDR SDRAMs in your design. I'm not sure, but I think there is
> no lower limit for the clock and you can implement your own SDRAM
> controller, which is easy, if you don't need the highest performance
> with burst-access, caching etc.

Ok, I think I see your point. It looks like worth of spending some time 
seeking for info about sdram world, if it's really easier than ddr.

I think I'll download an sdram datasheet (for example the psdram installed 
on the nexys2 board) to see if I could afford it and if the speed is 
comparable to that of a static ram chip. I think 15 or maybe even 20ns of 
"equivalent static ram" could be enough, if I can handle properly the T80 
signals in order to maximize the available time for the memory to respond. 
10ns would be really perfect but I don't think it's possible.

Thanks to everybody!
Alessandro

On Sun, 7 Sep 2008 23:24:22 +0200, "Alessandro" <apoppi@email.it>
wrote:

|I've also found  this interesting board 
|http://www.digilentinc.com/Products/Detail.cfm?Prod=NEXYS2&Nav1=Products&Nav2=Programmable 
|with 16MB of "cellular ram", or psdram, which can be accessed like an 
|asynchronous chip (self refresh is internally provided) but, unfortunately, 
|it's speed is 70ns in async mode.
|
|------------

Add $20 tothe base price and you get a XC3S1200 instead of the XC3S500
onthe NEXYS 2 board. Then you will have more than enough room for a
dual port SDRAM controller. I would still believe that the ZX would
fit well into the XC3S500 with a dualport SDRAM controller. 

james 

Alessandro wrote:
> 
> I saw this board a couple of weeks ago. Maybe a good choice now that I know 
> that sdram is simpler to drive than the ddr. That kind of sdram, 
> furthermore, can be accessed a static ram (slow: 70ns).

The whole point of the SDRAM is that it takes a while to set up
a read/write operation, but then a word is transfered on every clock.
Perfect for a video controller when you want to read the whole line
at once.

> 
> Do you think that the typical random access of an 8 bit microprocessor could 
> take advantage of the "sdram mode" over the 70ns "static ram mode"? I mean, 
> an average-design sdram controller could get more out of that chip than 70ns 
> in random rd/wr?

The controllers making SDRAM look like SRAM are very inefficient. They 
take 5-7 clocks for every word read/written. If you read consecutive 
words, it goes very much faster.

I don't quite understand the point in making a ZX Spectrum operate at
a high speed - you can't play the games and it's not exactly a perfect
platform for doing anything serious enough to require high speed,
but this is beyond the point. You can still use BRAM as cache. I suspect
with a couple of 16K such blocks most programs will never have a cache
miss :)


-Alex.

"Alessandro" <apoppi@email.it> wrote in message 
news:ga47np$am5$1@aioe.org...
> MikeWhy wrote:
>
>> Also take a look at Digilent's Nexys2
>> http://www.digilentinc.com/Products/Detail.cfm?Prod=NEXYS2&Nav1=Products&Nav2=Programmable.
>> $100 USD. Sounds like a good match except the FG320 package, 16 MB
>> SDRAM, and Xilinx platform flash. VGA output is 8-bit color only.
>
> I saw this board a couple of weeks ago. Maybe a good choice now that I 
> know that sdram is simpler to drive than the ddr. That kind of sdram, 
> furthermore, can be accessed a static ram (slow: 70ns).
>
> Do you think that the typical random access of an 8 bit microprocessor 
> could take advantage of the "sdram mode" over the 70ns "static ram mode"? 
> I mean, an average-design sdram controller could get more out of that chip 
> than 70ns in random rd/wr?

Actually, I wasn't aware of that; thought it was DDR for some reason. CL3 
SDR at 80 MHz does seem a bit challenged, maybe not even viable. I see they 
publish a Verilog simulation model. Might be interesting to see what speed 
you can get out of the processor. Do what you can with caching and bursts. 
Some stalling seems inevitable with any memory architecture.

Instruction and data on the same bus, 43 MHz, same cycle r/w? Would be 
challenging even for DDR2 at 133 MHz, I think.

I think I saw 10ns 1Mx8 TSSOP SRAM not very long ago for < $20. A quick look 
through DigiKey should answer that pretty quickly.

james wrote:

> Add $20 tothe base price and you get a XC3S1200 instead of the XC3S500
> onthe NEXYS 2 board. Then you will have more than enough room for a
> dual port SDRAM controller. I would still believe that the ZX would
> fit well into the XC3S500 with a dualport SDRAM controller.

I took a look at the micron psdram's datasheet; I suppose a dualport sdram 
controller is a piece of logic that translates an asynchronous access 
(microprocessor side) to a synchronous one (ram side).

You're not talking about using the blockram as a dualport cache, are you?

Ciao!

Alex Freed wrote:

> The whole point of the SDRAM is that it takes a while to set up
> a read/write operation, but then a word is transfered on every clock.
> Perfect for a video controller when you want to read the whole line
> at once.

I see.

> I don't quite understand the point in making a ZX Spectrum operate at
> a high speed - you can't play the games and it's not exactly a perfect
> platform for doing anything serious enough to require high speed,
> but this is beyond the point. You can still use BRAM as cache. I
> suspect with a couple of 16K such blocks most programs will never
> have a cache miss :)

:-) Now I've got the point. If I could have 64KB of bram, then the problem 
would be solved at least for "normal" use. Unfortunately this amount is only 
available on the 1600K gates chip. The reason for having a 21MHz zx-spectrum 
is, for example, ResiDOS which runs pretty fine on my cpld-based version of 
the clone, now being ported to fpga.

Anyway, yes... maybe I can slow it down a little. The other point was having 
not to deal with some complex and/or critical technology (and difficult 
packages) so that an hobbyst could assemble it's own machine, so a PQ208 and 
a static ram seemed nice.

Ciao!
Alessandro