[Coco] DE-1 Expansion Board Project - I need a suggestion

[richec]

On Tuesday, June 15, 2010 07:45:31 am sales at gimechip.com wrote:
> Steven,
> I'm laying out the PCB as we speak - actually I need to take a break and
> get a nap - Been working on it for hours - since I woke up yesterday. I
> hadn't included the battery as I received no response, but since I now
> have a response, I'll add the battery backup back in. I have included also
> a 40-pin IDE connector with the d0-d15 and a0-3 of the IDE interface
> connected to same signals of the SRAM - I am awaiting feedback to see if
> this is plausible. If if were not for you folks feeding me design ideas,
> I'd probably go bonkers sitting here at the house with nothing to do.
> 
> -John
> 
> 
> ----- Original Message -----
> From: "Steven Hirsch" <snhirsch at gmail.com>
> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> Sent: Tuesday, June 15, 2010 6:40 AM
> Subject: Re: [Coco] DE-1 Expansion Board Project - I need a suggestion
> 
> > On Mon, 14 Jun 2010, sales at gimechip.com wrote:
> >> Hey folks:
> >> 
> >> I've finished the 1Mx16 (2-meg total) SRAM design for the DE-1 Expansion
> >> board. I've also included the Analog Joystick circuitry as per Gary's
> >> request.
> > 
> > I think the CoCo community should elect you honarary hero!
> > 
> >> I had originally intended to include a battery backup for the SRAM.
> >> However, at present, I have removed it from the design. The reason being
> >> that the ISSI RAM chip specifies a 3.3V power source in order to operate
> >> at 8nS, which is important to the CC3FPGA project. The battery backup
> >> circuit introduces sufficient voltage drop to force the SRAM to it's
> >> 10nS access time. However, Gary suggested that I ask all of you if you
> >> might want the battery backup circuit added. If I add it back to the
> >> design, there would be a jumper to enable it, in which case the RAM
> >> would have a 10nS access time, battery backup disabled would allow 8nS.
> >> Let me know your thoughts.
> > 
> > I doubt a human would be able to detect a substantive difference in this
> > case.  My vote is for including the backup function.
> > 
> >> P.S. - I might to a similar board for the Spartan, since I have one of
> >> those - I don't have the DE-1 yet but I'm leaving Dad little notes
> >> around the house: i.e. "Wouldn't you like to buy your son a DE-1?" -
> >> hey, it worked when I was 7 :-)
> > 
> > Good luck with that one.  My folks told me to get a paper route...
> > (Probably dates me some, doesn't it?).
> > 
> > 
> > 
> > 
> > 
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 I juist now saw the post, I like the idea of a battery backup. Since I doubt 
anyone will be doing life threatening/supporting things with it, I don't think 
the speed difference will be that important. 8-)