TOKYO - Toshiba's CEO and eight other executives resigned Tuesday to take responsibility for doctored books that inflated profits at the Japanese technology manufacturer by 152 billion yen ($1.2 billion) over several years.Toshiba Corp. acknowledged a systematic cover-up, which began in 2008. Various parts of the Japanese company's sprawling business including computer chips and personal computers were struggling financially, but top managers set unrealistic earnings targets under the banner of "challenge," and subordinates faked results.On top of its struggles in electronics, Tokyo-based Toshiba's prospects in nuclear power, one of its core businesses, were shaken after the 2011 Fukushima disaster set off public fears about reactor safety, making new nuclear plants unlikely in Japan.