[Coco] FPGA CoCo's

Dave Philipsen dave at davebiz.com
Fri May 22 03:39:24 EDT 2015

On 5/21/2015 9:30 PM, Mark McDougall wrote:
> On 22/05/2015 11:10 AM, Dave Philipsen wrote:
>> Well, that's good to know. It's a shame that Altera changed the 
>> memory and
>> couldn't find a chip that is at least compatible with the old one.
> FTR the board is produced by TerASIC, not Altera.
True.  That's what I should have said.
>> Unfortunately, Gary doesn't publish the source and I'm not sure he 
>> has time
>> to keep up with it (although I don't know him personally nor have I
>> communicated with him).
> He did publish some early source, though I don't recall if that was 
> for the DE1 or not. I ported an early version of his Xilinx-based 
> project to the DE1 (older board) but that's very outdated now.
>> Anyway, it will be handy for other things IF I can get this stinkin SRAM
>> figured out.  It doesn't behave like most standard SRAMs and I 
>> frankly don't
>> have that much experience with VHDL to figure it out.
> Yeah I'm not really sure what the issue is as I have an older board.
After about 3 hours of trial and error this amateur VHDL coder got it 
figured out! (I'm sure a more experienced person would have figured it 
out in no time)  A few very minor changes to Grant Searle's project  
(which was written for a pretty standard 128K x 8 SRAM) makes it work on 
the new DE1 board.  The 256K x 16 SRAM on the DE1 now looks like 512K x 
8 to the Multicomp project and my MMU which works on another board with 
a 512K x 8 RAM now works on the DE1.

Next issue to tackle: make a file system to access the SD Card in FAT 16 
and eventually FAT32 formats.

> Regards,

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