Sinclair's C110 oscilloscope was an ingenious, well-designed and successful device developed by Bill Hardman, an electronics engineer recruited by Sinclair from another company, Neve Electronics. It used a TV tube originally developed by Germany's AEG Telefunken for the Sinclair Microvision pocket TV.

The device was housed in a remarkably small case - in fact, the same one used for the DM235, DM350 and DM450. Hardman recalls that Denis Taylor (a Sinclair director) asking him if there was a prize for getting it into such a small box! The prototype was constructed in just two weeks in order to allow Sinclair to take it to the United States for a sales trip. It was a considerable success and remained a steady seller for many years.