libhpcalcs: portable (Windows / MacOS X / Linux) connectivity kit library

[debrouxl]

Could you provide the full terminal output, presumably through tee, of a failed upload and a successful upload ?

Like the protocol used by TI-Z80 and TI-68k calculators, the protocol used by the Prime is not robust against packet losses "on the wire" (in the USB HID stack, mostly). There's no retransmit scheme. Unlike the computer, the calculator does not increment the first byte in the packet (at least, it didn't in the firmware from August), so calc -> computer packet losses cannot even be detected (beyond CRC mismatches).
While the Nspire's protocol doesn't have a retransmit scheme, each packet has a sequence number and a checksum.