Tom Verbeure Gets a Classic HP/Agilent Logic Analyzer Talking X to a Modern Linux Desktop
While permissive X Window connections may have been the norm in 2000, these days it takes a little more work.
Hardware engineer Tom Verbeure has given a classic HP/Agilent logic analyzer a new lease on life — by figuring out how to get a modern Linux desktop to talk to its vintage X Window System installation for remote operation and display.
"Produced sometime early 2000, it’s new enough to have an Agilent sticker," Verbeure writes of the HP 1670G, picked up at the Silicon Valley Electronics Flea Market. "Unlike most other HP logic analyzers, a 1670G doesn’t have expansion cards: what you see is what you get, but 136 channels that can be sampled at 500MHz is plenty, and my machine has the 2 channel oscilloscope option. A bandwidth of 500MHz and 2GSa/s sampling rate are very nice specs."
The device, described by Verbeure as being in "pristine" condition, is entirely usable as-is — though its use of floppy disks for data storage may raise a few issues if you rid yourself of 3.5" floppies already. The device boasts network connectivity, though, which would make it much more user-friendly — but its age presents some issues.
"[You can] operate the UI through an external X Window server," Verbeure explains. "It used to be easy to have any kind of X client connect to a remote X server. Back in the early 1990s on the HP Apollo workstations in college, it was a simple matter of setting the DISPLAY environment variable, but that was before network security was a concern. Things are bit more complicated now, and it took me a couple of hours to get the remote X server connection up and running on my Ubuntu 20.04 machine."
To get the device talking to a modern Linux system, Verbeure had to set a static IP address — the easy part — then figure out how to convince a modern, relatively locked-down X Window server to talk to the X Window client on the logic analyzer in order to bring up the user interface remotely. This required installation of the socat relay tool, the opening of firewall rules, careful routing of incoming requests to the system's current display, and the installation of font files specific to the logic analyzer. "This is super important," Verbeure notes. "Your logic analyzer will crash if you don't do this!"
With all that done, the machine's user interface should pop up on the Linux desktop for full two-way interaction — providing a much more convenient way to control it than the front-panel knobs and buttons, which Verbeure describes as "not a pleasant experience," without needing to find room for a dedicated keyboard an mouse.
This isn't the first time Verbeure has played with the inner workings of a vintage HP logic analyzer. Back in October last year he took apart an HP 16500A, figuring out a way to drive its compact 10" cathode-ray tube (CRT) display from external devices — with a little help from a local library's microfiche reader to get a look at the part's schematics.
Verbeure's full write-up is available on his blog.