[Coco] 256K RAM chips

[John Eric]

Dennis Weide once did and article in the Rainbow (I found it just the other day) for making a CoCo RAM Pak. You have to overcome the fact that CTS* is read only, so you have to do some memory mapping. His project was for the earlier CoCo's and as such was 16K. With the CoCo 3, you could make a 32k (or bankswitch 32k on a CoCo2). I have some of those chips as well and was considering an attempt at an internal 32k upgrade for an old zx81 I just found. J.eric




________________________________
From: N8WQ <exwn8jef at gmail.com>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Sent: Wednesday, December 31, 2008 7:38:21 AM
Subject: Re: [Coco] 256K RAM chips

John and James,
Sorry for the delay in getting back to you guys.
Thanks for all the information on my memory chips.
I knew they wouldn't actually work in the CoCo 3 but I thought they might be able to be used in some other creative way.
It just seems a waste to through these chips in the trash. I will keep them until some creative project comes my way.

Before I forget I hope everyone on the list has a Happy New Year.

I finally got all my CoCo's out of storage but I forgot to get my color monitor! :)
I will get it on my next trip.

Alan Jones

-- N8WQ - Canal Winchester, Ohio
http://exwn8jef.googlepages.com/home
http://n8wq.blogspot.com



John Eric wrote:
> Those UM61-256K-15 are in fact 256Kbit, 32Kx8 Static CACHE RAM chips. I several tubes of those. You might could use them to make a battery backed RAM Cartridge (32K) ??? JE
> 
> 
> 
> 
> ________________________________
> From: "jdaggett at gate.net" <jdaggett at gate.net>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Sent: Saturday, December 27, 2008 7:54:31 PM
> Subject: Re: [Coco] 256K RAM chips
> 
> On 24 Dec 2008 at 21:40, N8WQ wrote:
> 
>  
>> Can you guys tell me if I might be able to use these memory chips in a
>> Color Computer 3 project? Any ideas?
>> 
>> http://exwn8jef.googlepages.com/cocoprojects
>> 
>> Alan Jones
>>    
> 
> 
> Not without some means of demultiplexing the memory address from the Z-Buss. To achieve the 20 bit address you will need other logic and use the RAS/CAS signals to convert the 10 bit multiplexed address to a 20 bit address to use SRAMs. 
> james
> 
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