WP34s&Co. - an internal flashdisk

[pito]

Hi, have you ever considered an internal Flashdisk for storing the programs?

Assuming you have the firmware under your control you may define a simple protocol towards a small flashdisk, connected via the serial (when accessible via your firmware) and you may upload/download programs/data anytime to/from the flashdisk.

For example even a 256kB FRAM - 8 pin SPI device (or any other SPI flash memory), may store a lot of programs (or any other data) for you easily, I guess.

All you need to build the flashdisk is a cheapo low power 14/16pin 8bit mcu (the flashdisk controller), and the SPI flash/FRAM/MRAM chip.

The controller and flash will be placed inside the calculator and will be powered from the internal 3V battery, sleeping all the time, woken up when the serial sends him a command and the controller will then write/return the data required (based on an agreed protocol) into/from the SPI flash. The programs are small, so low baudrate must not be a problem (for example with 4800baud it takes ~5secs to load a 2kB large file into the calculator, but I do assume you may set the baudrate even to 115k2 when using the 32kHz resonator for the PLL).

The CSF here would be the willingness of the developers to provide the stuff for the calculator's side.. The flashdisk controller firmware to create would be a peanut then