DM42 News

[grsbanks]

(03-12-2018 04:37 PM)eulerfan Wrote:  I just had a thought. I suppose the operating system (Free42 + device drivers) is also stored on that flash drive.

There are two flash ROMs in the DM42.

There is one of 1MB within the STM32L476 main CPU and there is an external 8MB QSPI chip.

The O/S and all the executable code is in the STM32L476. The QSPI chip is divided into a zone of 2MB and the remainder of 6MB. The 2MB portion contains tables used by the Intel Decimal Floating Point library and other bits of static data. The 6MB chunk is the flash drive that you see on your computer when you plug the DM42 into your USB socket and activate "FAT Disk mode".

(03-12-2018 04:37 PM)eulerfan Wrote:  Is there a way to do a checksum or CRC on the OS to verify that it's intact?

Not on the O/S in the STM32L476, but a checksum of the QSPI's 2MB zone is performed at every machine reset to ensure that you have the right version of the QSPI contents to go with your version of the Intel library etc. If there is a mismatch then you are prompted to flash the correct QSPI version.

(03-12-2018 04:37 PM)eulerfan Wrote:  Does the DM42 have a reset button that forces a reboot?

Look on the back of the calculator