Write with "invisible" ink.
Invisible Video: Timex-Sinclair 1000, 1500 Authors Michael Allen Publication Enter Magazine Pub Details Volume: 1 Issue: 9 Date July/August 1984 Pages 55 Read the article Write with “invisible” ink. Products Downloadable Media Related Articles Tags Enter Magazine 1984 TS 1000 TS 1500 Type-in program People Michael Allen
