[Coco] 128K EEPROM Cartridge board

[Chad H]

Judging by prices of the PCB in the past (The new layout size is not expected change much so the cost should remain similar) and the cost of the sockets,etc..  I'm looking at keeping the $25 tag I've been making them under.

The whole flashing the EEPROM from the CoCo will take more research and experimentation as I have no experience with that.  That functionality shouldn't change the cost of the board though.

I've had to design PDIP and PLCC32 parts for the 29EE020 in Eagle since I couldn’t find it anywhere.  I checked and they are pin compatible with the 29EE010.  The 29EE010 just lacks the A17 line and is not connected.  This also means that I could easily design an 'adapter' for those that wish to flash these chips from a EEPROM programmer but only have the DIP socket and not the PLCC32 socket.   I've seen such adapters online but they are usually expensive.  I could make one for much cheaper.  Of course if we are flashing from the CoCo it wouldn’t' be needed.

- Chad

-----Original Message-----
From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of David Ladd
Sent: Sunday, January 25, 2015 11:55 AM
To: CoCoList for Color Computer Enthusiasts
Subject: Re: [Coco] 128K EEPROM Cartridge board

Chad,

I personally like this idea :D
I would love to have a independent programmable program pack with banks.
This would allow me to make use of my CoCo2B that has issues till I can get around to fixing it. :D

You have a fully assembled cost idea so we know how much to expect that we would need to give to get such a product from yeah? :D  Thanks :D





On Sun, Jan 25, 2015 at 10:28 AM, Chad H <chadbh74 at hotmail.com> wrote:

> I was browsing prices on the 2764, 27128, 27256 and 27512 EPROMs this 
> morning noticing how they are slowly getting more scarce, especially 
> the 27128.  Also, the prices are not the best.  Ironically, at least 
> to me, the 27512's with most capacity are the cheapest.
>
> Then I remembered I had a box of like 20 or so 29EE010 EEPROMs that I 
> had ordered a few years ago. I only needed one to upgrade my Win'98 
> machines bios chip but was cheaper to buy the lot.  In any case, these 
> are 128k parallel EEPROMs 150ns in the DIP 32-pin package and go for 
> about $1.70 easy.  Even better, I can get the PLCC version for $0.25.  
> I know my old Willem programmer works with them and I wouldn't have to 
> wait on UV erase cycles.
>
> I have the idea of revamping the 2764-27512 EPROM boards I've been 
> building, removing the existing DIP layouts and adding the option to 
> mount either the DIP or PLCC version of the 29EE010.  I would also 
> need to add one additional jumper for the A16 address line.  This 
> would give more capacity for roms , each selectable by jumpers...
>
> 16 x 8K
> 8 x 16K
> 4 x 32K
>
> I'm going to go ahead and work up some prototypes on this.  I'm 
> wondering how much interest would there be out there in this?
>
> - Chad
>
> Sent from my Transformer Infinity
>
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