2022-09-28

Yesterday while setting up the file transfer between the HP 95LX and the Linux box I noticed that I'd bent one of the pins on the 95LX's serial connector. Luckily it was one of the outer pins, not the inner two which actually carry data. I returned it into the correct position with some difficulty, using tweezers.

Besides, it appears that the XMODEM transfer is up to twice as fast sometimes. Data rates of 1 KiB/s are possible. It seems like connecting the (9V AC) power adapter that came with the second 95LX may be the cause of this. In either case the baud setting numbered 7, called "Direct", of 57600 baud is selected. At a rough estimate a stop bit plus eight data bits makes for 9 bits per byte, so 57600 baud / 9 bits/Byte = 6400 Byte/s. I assume the bad performance of the XMODEM protocol may be why we get 6 to 12 times less than the theoretical rate.

Unfortunately, the Public Domain ZModem (PDZM) application does not seem to work on the 95LX, not even when specifying the -d -h switches. It seems to wait until timeout, never starting the transfer. I assume it may be because of the lacking hardware flow control wires. The output window on the screen was a solid black blob with some white text, potentially usable.

Today the mail shipped the replacement backup battery tray parts. I inserted one into the second 95LX along with a CR2032 battery (plus side down). It appears to fit.