The Tektronix 5403 is a 60 MHz scope mainframe base unit that uses 5000-series plug-ins. It allows CRT readout of settings when used with plug-ins that support this. Most 60 MHz plug-ins and time bases do.
It was sold preconfigured with a display unit:
- a D40 single beam unit would make it a 5440 single beam (but multi-trace, depending on plug-ins) oscilloscope,
- a D41 storage display unit would make it a 5441 CRT storage scope,
- a D44 dual beam display unit would make it a 5444 dual beam oscilloscope.
Many scopes have a nameplate on top carrying the 5403 base unit model number instead of the full model (5440, 5441, 5444), sometimes confusing owners.