ExtraBITS this week span the gamut, starting with Tonya Engst’s appearance on the Tech Doctor Podcast, Cult of Mac’s comparison of print and ebook prices for textbooks, some juicy Apple secrets revealed in the Apple-Samsung patent suit, a site that lets you navigate recent Mars photos using an iOS device’s gyroscope sensor, Lex Friedman’s explanation of how to turn on Google’s two-factor authentication, and a collection of reminiscences on HyperCard’s 25th anniversary.
 -- Take Control editor-in-chief Tonya Engst joined Robert Carter of the Tech Doctor Podcast to talk about how the Take Control ebook series has evolved from its inception in 2003 to today’s world of EPUB and iOS devices. The Tech Doctor Podcast has a focus on helping people with visual disabilities use technology, and at the end, Robert Carter demos using VoiceOver to read a Take Control ebook out loud on a Mac.
 -- When it comes to saving on the cost of textbooks, college students might be well advised to invest in an iPad: Buster Heine provides cost comparisons between ebooks and print books for some typical students. (Appalling: an etextbook that costs $139.01. More appalling: the print version of the same book that costs $239.75!)
Wall Street Journal includes a fascinating slideshow of iPhone prototypes and other interactive media. Both are worth checking out. -- We’re a few days late in posting these links, but it’s nonetheless interesting to read the technology gossip coming out of the Apple-Samsung patent trial. Nick Bilton of the  frames the Apple-Samsung trial with an unsuccessful 1930’s patent suit to protect the illusion of sawing a woman in half, whereas the piece by Ian Sherr of the
 -- Viewing the photos sent back from NASA’s Mars Curiosity mobile science laboratory has been exciting over the last week, but here’s one with a twist… and a roll. Open this link on an iOS device that contains a gyroscope sensor — like the iPad 2 and third-generation iPad, iPhone 4 and 4S, and fourth-generation iPod touch — and navigate the panorama by tilting and moving the device. (Bonus points for scanning the horizon while you’re sitting in a swivel chair!)
 -- Over at Macworld, Lex Friedman explains how to turn on and use two-factor authentication with a Google account to combine a fixed password with a constantly updated additional code sent as a text message or accessible from a smartphone app. Be aware that two-factor authentication may be more trouble than it’s worth, depending on how often you need to sign into your Google account.
 -- On 11 August 1987, Apple released the “software erector set” HyperCard at Macworld Expo in Boston, and while it hasn’t been with us for many years now, back then it made a huge difference in the lives of Mac users, enabling many to give life to ideas that would otherwise never have seen the light of day. That might include even TidBITS, since we published our first 99 issues in HyperCard format, in a stack that could import its content into a searchable archive. Without the thrill of publishing in an entirely new format, it’s possible that TidBITS might have fallen by the wayside. Scroll through what others have posted in this Twitter search, and be sure to check out  on the iPad too!