"Portable" personal computers have been around since before the IBM PC but the "Compaq Portable" (1983) - affectionately called a "luggable" - really started the revolution so many years ago. By the late 1980's, Toshiba was selling "laptops" which still required plug-in power.
By the 1990's battery-powered laptops were widely available but still quite expensive.
During the first decade of the new century notebooks had become the new standard in low-cost high-performance. Though the term "tablet" was associated with with high-end PCs for most of the decade - until the Apple iPad came along.
All that said, the tablet is really just the new "thin client" ... a portable device intended to deliver content from the clouds via this applications.
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