Spectrum plus 48kZX Spectrum+ 48KPlanning of the ZX Spectrum+ started in June 1984, and was released on October 15th. This 48 KB Spectrum (development code-name TB) introduced a new QL-style case with an injection-moulded keyboard and a reset button that was basically a switch that shorted across the CPU reset capacitor. Electronically, it was identical to the previous 48 KB model. It was possible to change the system boards between the original case and the Spectrum+ case. It retailed for £179.95 (equivalent to £583 in 2019). A DIY conversion-kit for older machines was available. Early on, the machine outsold the rubber-key model 2:1; however, some retailers reported a failure rate of up to 30%, compared with a more usual 5–6% for the older model. In early 1985, the original Spectrum was officially discontinued and the ZX Spectrum+ was reduced in price to £129.95 (equivalent to £397 in 2019).

Wikipedia ZX Spectrum + 48 K