What Was the Refresh Rate of the Sinclair ZX Spectrum +3?

This article explores the technical specifications of the Sinclair ZX Spectrum +3, specifically focusing on its video output capabilities. We will examine the hardware architecture responsible for generating the display signal and confirm the exact screen refresh rate used by this classic home computer. Readers will learn why the frequency was set to 50 Hz and how this related to the PAL television standard prevalent during the 1980s.

The Sinclair ZX Spectrum +3, released in 1987, was designed primarily for the European and British markets. Consequently, its video output was engineered to be compatible with standard PAL television sets. The Uncommitted Logic Array (ULA) chip within the machine handled the video generation, synchronizing the display with the local broadcast standards. This ensured that users could connect the computer to their home TVs without requiring specialized monitors.

As a result of this PAL compatibility, the refresh rate of the video output on the Sinclair ZX Spectrum +3 was 50 Hz. This frequency matched the field rate of PAL systems, providing a stable image on compatible displays. While NTSC systems in North America utilized a 60 Hz refresh rate, the +3 remained fixed at 50 Hz, distinguishing it from earlier Timex Sinclair variants produced for the US market. This specification remained consistent across the standard production run of the +3 model.