Fax hard to operate. In 1966, Xerox released the Magnafax Telecopiers, a smaller, 46-pound facsimile machine. This unit was far easier to operate and could be connected to any standard telephone line. This machine was capable of transmitting a letter-sized document in about six minutes. The first sub-minute, digital fax machine was developed by Dacom, which built on digital data compression technology originally developed at Lockheed for satellite communication. By the late 1970s, many companies around the world (especially Japanese firms) had entered the fax market. Very shortly after this, a new wave of more compact, faster and efficient fax machines
Black fax Black fax The term black fax refers to a prank fax transmission, consisting of one or more pages entirely filled with a uniform black tone. The sender's intention is generally to use up as much of the recipient's fax ink, toner, or thermal paper as possible, thus costing the recipient money and/or denying the recipient use of their own machine (this is similar to computer-based denial of service attacks). This is made easier because the fax transmission protocols compress the solid black image very well, so a very short fax call can produce many pages. Black faxes have been used