TYPO?

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An excerpt from PDAs: Revolutionizing The Way We Learn and Teach , Turkish Online Journal of Distance Education-TOJDE April 2006 ISSN 1302-6488 Volume:7 Number:2 Article:14 pages 153-154

TECHNOLOGIES AND INFRASTRUCTURE
PDAs have evolved over the last two decades starting in 1974 with Hewlett Packer’s release of the HP-45 calculator, which could be programmed¹, included a timer², and had removable storage³.
?¹ ?² ?³

BEST!
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ps: yes, there is an embedded tyypo, but the Subject: TYPO? refers to ?¹ & ?³!