[Coco] Introduction

[John Kent]

Hi Jayeson,

The Spartan 3 Starter board from Digilent-Inc has 1MByte of high speed 
static RAM on it that can be configured as 256K x 32 bits. It would be 
better as a logic analyzer than the XuLA board, as the RAM is 
asynchronous and doesn't need refresh cycles.

It is possible to buffer the input on the XuLA board, with block RAM but 
then you have the problem of crossing clock domains between the input 
sample clock and the SDRAM clock. I'm not sure if that is a big problem 
with dual ported block RAM. Dave Vanden Bout from XESS did tell me one 
of the original applications intended for the XuLA board was as a logic 
analyzer.

The XuLA board does have the advantage that you have a USB connection to 
the PIC chip on the board so it's much faster transferring data than 
using a RS232 port.

Both the XuLA and Digilent-Inc need level conversion for the inputs but 
that is self evident.

I'm sorry for the length of the last email. I was pretty much repeating 
what has already been stated on the list.

John.

On 24/02/2013 11:43 PM, Jayeson Lee-Steere wrote:
> John,
>
> Thanks for the info. You are getting years ahead of me! I was thinking that
> attaching one to the Coco cartridge connector port and programming the FPGA
> to log bus activity into the SRAM would be good for creating accurate
> timing reference for software emulations. That is sounds fairly simple and
> in my comfort zone. Anyway, I ordered the 200K gate version. Still need a
> prototyping board with the card edge though...
>
> - Jayeson
>
>

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