[Coco] Today, I have seen the CoCo 4...

[Steven Hirsch]

On Thu, 27 May 2010, Frank Swygert wrote:

> I was wondering what the SRAM was used for! Other than power and retaining 
> memory powered down, is there any real reason to use SRAM instead of standard 
> DRAM SIMMs on a specially designed board? The CoCo will support at least 2MB, 
> but isn't there a simple hack to allow a max of 4MB (adding an address line 
> or two, IIRC)? Incorporating that in a new design would be ideal, then use a 
> readily available SIMM. Two memory slots should be sufficient if the slots 
> can be made to support from 256K-2MB SIMMs. That would at least make initial 
> cost a bit lower, though memory isn't really so pricey that a board with 4MB 
> would be all that much higher than one with 512K. Not when the overall price 
> of the board is considered. But someone just wanting to run DECB wouldn't 
> really need more than 512K, OS-9 on the other hand benefits from maxing out. 
> If there has to be a choice the board should be optimized for OS-9 
> (Nitros-9), as the majority of users will probably be running that. As far as 
> I kn
> ow there is nothing that OS-9/Nitros-9 does that would hamper DECB operation.

DRAM, particularly modern DDR types, is significantly more difficult to 
interface with and may require an excessive number of additional gates. 
Otherwise, I agree.


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