[Coco] 512K EEPROM...or 4MB!!?

Wed Dec 9 00:10:42 EST 2015

Again, with the addressing control setup for parallel EEPROM's (Which interface seamlessly with the CoCo Cartridge BUS), breaking it down further for 2K access or whatever would further complicate the entire circuit.  The minimum chunk size (because nothing lower than the A13 address line is controlled) is 8K.  The hardware/software can already vary the control over the A13/A14 lines to switch in 8K/16K/32K segments, but even then you have to follow the rules of the lines so to speak.  You can't just chop a segment anywhere you like, it has to be at the address boundaries, unless you write a lot of assembly code embedded into the ROM sections like some games (MindRoll) do in order to execute mid-bank.  My Arduino code can already boot whichever 8K-32K bank you have set to for 'Default' automatically.  Plus, the source code is available for download for anyone to tweak and customize.

The 4MB option is just a concept at this point.  The 512K setup is tested solid and is working great.  I already know that, in order to make the TSOP40 chip I'm looking at practical, there will be small cost increase due to making an adapter to allow the soldered SMD chip to be removed for programming.  Even if we soldered it directly to the cartridge board and made it programmable by the CoCo, there would be other extra costs for the required IC's and probably board space increase necessary to support that functionality.

My goal is to maximize storage space and make it as easy as possible to switch .ROM's at will while keeping the design as simple as possible and cheap as possible.  The jumper control is simple and cheap, the external controller makes it much simpler but not quite as cheap.

I'm thinking some people would like to just leave off the external controller and program/select ROM's from the CoCo...That's a CoCo SDC, although it only has 128K in-system-programmable Flash.  I think Zippster did a batch of those last year with permission from Darren Atkinson, the designer.  Perhaps more can be made for those that desire one, maybe even the Flash memory expanded on it. Whereas the CoCo SDC is really more of a 'Combo' all-in-one kind of card as a floppy replacement/EEPROM board my focus was on making a EEPROM board with as much bank selectable storage as possible, easily controlled, and that’s it.  For me, my EEPROM boards are just an evolution from Mark J. Blair's original EPROM boards. I just kept adding on to the design little by little until I decided to remove the old 24/28 DIP sockets and bump up to larger capacity type chips and the option of external remote control.  The schematics for my boards are available in the BOM documents on my site if anyone would like to do the same thing and progress it further with the ability to be programmed from the CoCo, but I imagine it would require a major overhaul of the design.

- Chad H
http://sites.google.com/site/cbhlab101/

-----Original Message-----
From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of Camillus
Sent: Tuesday, December 08, 2015 9:45 PM
To: Bill Pierce via Coco
Subject: Re: [Coco] 512K EEPROM...or 4MB!!?

Yes, I like this very much. And to be honest it was one of my ideas to build something like this years ago.
Now I'm only have to pay you for the work...LOL

For my $0.02 worth opinion, maybe go with the one 4MB chip, then use the first 2K or more for a selection monitor controller program that does the same thing as your external arduino, but then on the coco.( starts like an normal cartridge). Rewrite your Arduino code or make use of Logicall ( or wat was the name of that nice boot loader program?). The software need to be tweaked of course so it select one out the many images and setup the right address selection.

Also does it need to be an EEPROM, a couple of cmos SRAM or not so killing expensive anymore, and a lithium cell 3.5 volt goes a long way. This gives you the opportunity, to have people program there images directly from the coco. ( option programming in yourFW or Logcall ).

Basically what I'm trying to say is combine your project...LOL

The more I write about it the more I want to design it, but thanks to you we can have something to play with, and it is a really awesome project, thanks a lot for the effort.  

Keep up the good works.

cb

PS I will order a board from you soon.

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On 12/8/2015 8:23:32 PM, Chad H <chadbh74 at hotmail.com> wrote:
Today I was looking at EEPROM chips and stumbled upon a 4MB chip that meets all the criteria for what I could consider to be a candidate for a EEPROM board. My current boards support up to 512MB via PLCC32 or DIP32 socket but the 4MB would require some creative adapting with its TSOP40 layout. In order to make practical, I could design a tiny adapter board to solder it to, giving it legs so to speak, that could be plugged into the EEPROM board or a special adapter for programmers such as the TL866 or GQ-4X. I'm wondering though if this is 'too much'. We can fit quiet a lot of .ROM/.CCC/.BIN stuff in the 512K chips already, but 8 times as much? Then again.is there such a thing as too much space?

I've got a itch to persue this and see if I can make some sort of 'Mega-Flash' version of the EEPROM boards around this chip. I could even keep the existing External Controller interface. Because it uses serial address control, no changes would have to be made there. I'm just not sure if I could even find enough games and utilities in .BIN/.ROM/.CCC format to even fill such a chip.

Thoughts anyone?

- Chad H

http://sites.google.com/site/cbhlab101/

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