[Coco] Introduction

[Richard E. Crislip]

On Sunday, February 24, 2013 08:35:28 AM John Kent wrote:
> 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

Don't be sorry! Even I understood most of it 8-). I haven't even touched a 
FPGA. Excellent explanation. When you mentioned Switch/Case constructs, I even 
know what that was all about. You see them in the Bash Shell and C++ 8-).

Richard