[Coco] 512K/1M/2M512M CoCo 3 Upgrades - Some Work Towards That Goal

[Little John (GIMEchip.com)]

I have just finished wire-wrapping a standard 30 pin simm upgrade for the
CoCo 3 and am using the SIMMs from my recently acquired Cloud-9 512K upgrade
to test it with. So far it is passing all of the tests from the Performance
Peripherals 512K Memory Test program. I am using this memory test program
because it has a test specifically targeted at testing the memory's ability
to retain refresh. As I am now satisfied that this standard wire-wrapped
512K simm upgrade functions properly, I am about to add the 16V8 GAL to the
wire-wrapped mess that I now have. This will allow me to test whether or not
my refresh equations within the GAL are actually functioning. I will replace
the simms with the 3-chip kind and some odd 2-chip ones that I've found. If
this test passes, then I'll be able to produce the 2-Meg upgrade. I'll post
the results in a half hour or so. -John
----- Original Message ----- 
From: "Little John (GIMEchip.com)" <sales at gimechip.com>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Friday, July 09, 2010 6:55 PM
Subject: [Coco] 512K/1M/2M512M CoCo 3 Upgrades - Some Work Towards That Goal


>I have posted some of this here:
>
> http://www.coco3.com/community/2010/07/more-on-coco-3-memory-upgrades-512k1m2m-from-gimechip-com
>
> I am hoping fellow list members may be able to spot potential problems 
> with this design. I hope to get a functional 2-Meg upgrade ready soon, but 
> I've got to test these equations first. - Thanks All - John
>
> This is my proposed method of allowing the use of DRAM requiring a 
> 512-Cycle refresh in a CoCo 3 512K/1M/2M RAM Upgrade. If I have gotten 
> this correct, then it should be possible to make a 5-chip 512K RAM Upgrade 
> (four 256Kx4 DRAMs plus the GAL 16V8), or to use Any 30-Pin or 72-Pin 
> SIMMs in a CoCo 3 SIMM Upgrade. The Equations below should tell the story 
> if you examine them, or preferably, download the WinCUPL file for better 
> formatted text. Simply unzip the download and load the ".pld" file into 
> WinCUPL or a text editor. Let me know if you spot anything that seems as 
> if it will not work. Getting these equations working properly (I have yet 
> to test them) is the key to my proposed 2-Meg and 512-Meg Upgrades. Once 
> the memory board has been worked out, the DAT Board is child's play - you 
> could simply Copy DISTO's DAT Board, but my design uses a SRAM and 
> Multiplexers, etc. and also allows the added DAT bits to be read back 
> (they are write only in DISTO's 2-Megger). I have generat
> ed PCB Layouts for both a 5-chip 512K and a 30-Pin SIMM 512K Upgrade 
> intended to use the PAL generated from these equations, however all of 
> this needs to be tested before I decide to order any boards - I'm hoping 
> you guys can let me know if this looks feasioble and correct.
>
> Thanks All - John
> 512KAnySIMM_PLUS_512K-44256_PLD-Equations(GIMEchip.com)
>
>
>
>
>
> http://www.coco3.com/community/2010/07/more-on-coco-3-memory-upgrades-512k1m2m-from-gimechip-com
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco


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