[Coco] FW: Attempting to upgrade a CoCo2

[Arthur Flexser]

Kip,

My recollection is that a 68766 is basically a slightly faster version
of the 68764, so I'd think the burning process would be the same for
both.

Art

On Sat, Oct 5, 2013 at 4:53 AM, Kip Koon <computerdoc at sc.rr.com> wrote:
> Hi Mike!
> You will have to find someone who either has a 24 pin mask programmed rom
> from Tandy for ECB 1.1 or program an MCM68766 8K x 8 bit eprom with ECB 1.1
> or get a 24 pin to 28 pin eprom adapter and program a 2764 8K x 8 bit eprom.
>
>  I found my Color Burner which can burn MCM68764s, but I have never burned a
> 68766 yet.  I need to see how close to a 68764 the 68766 is.  I bought some
> recently, so I plan to play with them and see how it goes.
> I also just created a 24 pin to 28 pin eprom adapter that will hold a 2764
> 8K x 8 bit eprom.  I haven't tested it yet in my disk controller to hold
> HDB-DOS.  It is designed to replace the MCM68364 mask programmed roms Tandy
> used on the motherboards, disk controllers and some rom cartridges.
> If you'd like, I'll go ahead and test it and see how it does.  It should
> work as the circuit is pretty simple.  I have been exploring making PCBs of
> late and this is my third or fourth PCB I've made.  I'm having a lot of fun
> with it.  Take care my friend.
> Kip
>
> -----Original Message-----
> From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] On
> Behalf Of Mike Craig
> Sent: Friday, October 04, 2013 9:55 PM
> To: coco at maltedmedia.com
> Subject: [Coco] Attempting to upgrade a CoCo2
>
> Hi Everyone. I recently got my paws on a CoCo2 16k 26-3134. I'm going to
> hunt down a 2716 Eprom and program it with ECB tomorrow. I'm lucky in the
> fact that I have a surplus company around the corner from with with parts of
> all kinds. Question I have is about the RAM upgrade. The eight RAM chips are
> 8040517's and from what I understand, I have to replace them with 4164 chips
> of 200 ns or better access time, and to solder a wire between the two pads
> labeled J1. I'm assuming that all eight chips need to match speed wise. I
> did a search on Ebay and see lots of them listed. I have my eye on these
> 'NEC Dynamic RAM Memory 64K x 1-Bit UPD4164C-15'. Would those work? And am I
> barking up the right tree so far? :D
>
> Thanks,
>
> Mike
>
>
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