screen, and information could only be taken from the memory onto the screen. Five keys were used for memory operations. The Sovereign used a Mostek MK50321N main integrated circuit, the same as the Sinclair Wrist Calculator and some variants of the Sinclair Cambridge. Clive Sinclair had assumed that people would prefer attractive illuminated LED displays to LCD displays, which incidentally also required more expensive CMOS chips. However, his calculators were designed with the assumption they would be turned off between calculations, which did not prove to be the case. Advertisements suggested that the batteries would last "about a year" under normal use, but in reality the small button cell batteries and comparatively high power consumption meant a short battery life compared to the competition. References Citations Sources External links 1976 Sinclair Sovereign LED pocket calculator at YouTube Computer-related introductions in 1976 Sinclair calculators