Thor-CD

Thor-CD was a re-recordable CD format proposed in 1988 by Tandy Corporation.{{cite news|last1=Lazzareschi|first1=Carla|title=Tandy Develops a Compact Disc That's Erasable|url=https://www.latimes.com/archives/la-xpm-1988-04-22-fi-1732-story.html|access-date=5 February 2018|work=Los Angeles Times|date=22 April 1988}}

Prior to the introduction of recordable compact discs, Tandy announced a comparable CD format named Thor-CD,{{cite web| url=http://www.technofileonline.com/texts/thorcd88.html| title=Why Tandy's recordable CD is a breakthrough even if it never makes it to the market| first=Al| last=Fasoldt| year=1988| accessdate=2006-03-06}} otherwise known as the Tandy High-Density Optical Recording (THOR) system, claiming to offer support for erasable and rewritable discs, made possible by a "secret coating material" on which Tandy had applied for patents,{{ cite magazine | url=https://archive.org/details/electronics-1988_04_28/page/21/mode/1up | title=Tandy Challenges Thomson In Race To Market Erasable CD Systems | magazine=Electronics | date=28 April 1988 | access-date=18 October 2022 | pages=21 }} and reportedly based partly on a process developed by Optical Data Inc., with research and development undertaken at Tandy's Magnetic Media Research Center.{{ cite magazine | url=https://archive.org/details/sim_eventdv_1988-07_1_2/page/11/mode/1up | title=Laserdisk News | magazine=Laserdisk Professional | date=July 1988 | access-date=18 October 2022 | pages=11–12 }}

Also known as the Tandy High-Intensity Optical Recording system, THOR-CD media was intended to be playable in existing CD players, being compatible with existing CD audio and CD-ROM equipment, with the discs themselves employing a layer in which the "marks", "bumps" or "pits" readable by a conventional CD player could be established in, and removed from, the medium by a laser operating at a different frequency.{{ cite magazine | url=https://archive.org/details/radio_electronics_1988-08/page/n7/mode/1up | title=News | magazine=Radio Electronics | last1=Lachenbruch | first1=David | date=August 1988 | access-date=18 October 2022 | pages=6 }} Tandy's announcement was surprising enough to "catch half a dozen industries off guard",{{ cite magazine | url=https://archive.org/details/1988-07-compute-magazine/page/n7/mode/2up | title=Tandy Announces Micro Channel Machine, Springs CD Surprise | magazine=Compute! | date=July 1988 | access-date=18 October 2022 | pages=6–8 }} claiming availability of consumer-level audio and video products below $500 by the end of 1990, and inviting other organisations to license the technology.{{ cite press release | url=https://archive.org/details/Message_of_the_Day_1988-03_OS9_Users_Group_US/page/n20/mode/1up | title=Tandy Corporation Announces Major Breakthrough In Optical Media: Tandy THOR-CDTM, The First CD-Compatible Record & Erase Technology | publisher=Tandy Corporation | date=21 April 1988 | access-date=18 October 2022 }}

Tandy's announcement attracted enthusiasm but also skepticism of Tandy's capability to deliver the system, with the latter proving to be justified, the technology having been "announced... heavily promoted; then it was delayed, and finally, it just never appeared".{{ cite magazine | url=https://archive.org/details/sim_eventdv_1997-01_10_1/page/27/mode/2up | title=DVD-ROM: Who Needs It, Who Will Use It, and How? | magazine=EMedia Professional | date=January 1997 | access-date=18 October 2022 | last1=Parker | first1=Dana J. | pages=26–28, 30–32, 34–37 }} After being pushed back for several years, it was finally cancelled due to steep manufacturing costs.{{cite news|last1=Hayes|first1=Thomas C.|title=Tandy Ventures Into the Unknown|url=https://www.nytimes.com/1992/10/27/business/tandy-ventures-into-the-unknown.html?pagewanted=all|accessdate=5 February 2018|work=The New York Times|date=27 October 1992|quote=Its foray into compact digital recorders with a product known as Thor-CD fizzled because manufacturing costs were too steep.}}