Screen reading software is usually memory resident. It can be programmed to locate individual letters, words, lines or sections of text. Examples of speech synthesisers, all by the UK company Dolphin Systems . Magnification systems may be software or hardware based. Software systems are memory resident.
Some systems also allow background colours to be altered and others provide screen reading.
There are both standalone scanners which have their own speech output and ones which link to the PC compatible. The OCR consists of a flat bed or hand held scanner, and software to convert the image into machine readable form. The computer or reading aid can then store this as a file or reproduce it via speech synthesis or Braille if Braille translation software is installed. These systems vary from simple magnifiers to very sophisticated models which can be linked to a computer or television set. A Braille keyboard can replace the conventional keyboard.