Popular on eBay are old test equipment like Spectrum Analyzers, Oscilloscopes, and Multimeters. HPDisk by Gustafsson Anders creates a virtual GPIB interface that stores data to a SD-Card.This is done by emulating a special HP disk drive, that some HP instruments know how to write to when connected. (As Anders points out, this is not emulating a built-in floppy drive.)

Keep reading if you aren’t familiar with GPIB.

What’s GPIB?

Long before USB became the standard I/O interface in the computing world, bench-top instruments used HPIB. This was the “HP Interface Bus” used by Hewlett-Packard in the early days of their test equipment. It enabled instruments to share data and be automated by “desktop computers”.

Eventually HPIB evolved into GPIB and the IEEE-488 standard was created. Until about 2000, most instruments supported a true GPIB/IEEE488 hardware connector. Slowly that evolved into USB-based virtual connectors (like a virtual serial port).

Oscilloscopes are the most critical tool when it comes to debug and analysis of electronic circuits.  In recent years, digital oscilloscopes finally surpassed their analog equivalents.  (10 years ago I would still make an argument for analog, but not anymore.)

The most innovative change to digital scopes came with “Mixed Signal Scopes.”  In addition to the high-resolution analog channels, you get 16+ digital channels time-correlated.  Digital channel in this context means only seeing a 0 or 1, kind of like a logic analyzer.

Rigol’s MSO1104Z combined 100MHz of Analog Performance on 4 channels along with 16 Digital Channels for $1000 (MSRP: $997) USD!  That’s an amazing package.  Full specs and Quote request available here.