DM42 Firmware Update on a Mac

[ijabbott]

In addition to what Thomas_Sch wrote above, it may be easier for you to upgrade to V3.5 first since it is all in one piece. Then further upgrades can be done by the FAT method. Actually, there is no real benefit in upgrading from V3.5 to V3.7 if all you want to do is use the calculator, as there are no bug fixes between the V3.5 and V3.7, just organisational changes.

Since installing dfu-util for a one time use may be a bit of a faff, it may be easier to find a friend running Windows 7 who is willing to help you update the firmware. (There are some problems with drivers when doing this on Windows 10. There are workarounds that leave Windows 10 in a slightly compromised state, so it would be unfair to borrow a friend's PC for this task.)