[Coco] 256K SuperROMPak (32 Banks)

[Chad H]

I received a batch of test boards in from OshPark to test out my 256K
EEPROM's and reading the chips worked great.  I hacked and hacked at it
trying to get figure out how to get the CTS, WE, and RTS lines working
properly to allow writing to the chip from the CoCo then I stumbled upon
some old posts from this list in 2007 talking about how the lines were not
designed to do 'writing' and you would have to come up with other means to
do it.  I guess this is what the CoCoSDC  and others have done with extra
circuitry and logic chips.  Unfortunately this is beyond me at this point in
my learning process.

 

However.  since the chips do read well I've decided to re-invent the concept
of what I want these boards to be around what I've got experience with and
what I know I can make into a working unit...

 

** 256K EEPROM 29E0020 (Atleast can skip the UV Erase when re-programming)

** 16 x 16K BANKS or 32 x 8K Banks!

 

** Writing/Flashing?:  REMOVED

** Address line jumpers for banks:  REMOVED

 

To be Added..

** Atmega Controlled Bank selection with selector buttons and LCD Screen.

 

The plan is to have a pull down resistor for the HALT line upon power up to
'PAUSE' the computer until the Atmega can select the default bank of your
choice, which is the last bank you used.   When you change banks, the LCD
will start flashing the banks indicating that the change is not active.
Press a button on the board to reboot the CoCo (via the RESET line) at which
point the Atmega will switch to the new ROM bank and set it as the new
default.  You could also press the UP/DOWN buttons at the same time to
switch 8K/16K mode.

 

This is the plan as it stands.  I'm confident I can do this kind of setup.
I've done much more complex things with Atmega 328's.  Would anyone else be
interested in a EEPROM board with graphically/button selectable ROM banks as
opposed to the old jumper style selections?    Now by default the display
would show "16K:  Bank #1" or whatever number you have selected but for
those familiar with Atmega328's, especially Arduino's, I could provide a
FTDI connection and a sketch to allow the user program in the names of the
ROM's instead of just the bank numbers.

 

Ideas and suggestions are welcome.  I've got a lot of redesigning to do.

 

-          Chad