PART 6

• PHYSICAL CONTROLS • specialist controls needed … • industrial controls, consumer products, etc.
• Resolution, Speed and COST.

  these are the Critical features of Printing
• PRINTING • image made from small dots which allows any character set or graphic to be printed
• THERMAL PRINTERS special heat-sensitive paper, poor quality, but simple & low maintenance
• SHOP TILLS dot matrix and same print head used for several paper rolls
• FONTS • refers to the particular style of text • Size of a font measured in points (1 pt about 1/72”)
• lowercase • easy to read shape of words
• UPPERCASE • better for individual letters and non-words e.g. flight numbers: BA793 vs. ba793
• serif fonts • helps your eye on long lines of printed text • but sans serif often better on screen
• WYSIWYG • what you see is what you get • aim of word processing, etc.
• WYSIWYG • what you see is what you get • aim of word processing, etc.
• SCANNERS • Take paper and convert it into a bitmap (Colored or Grayscale) • Used in o desktop publishing for incorporating photographs and other images o document storage and retrieval systems, doing away with paper storage o special scanners for slides and photographic negatives
• HAND-HELD SCANNER scanner passed over paper, digitizing strip typically 3-4” wide
• FLAT-BED SCANNER paper placed on a glass plate; whole page converted into bitmap
• OPTICAL CHARACTER RECOGNITION • OCR converts bitmap back into text • Different font may create problems for simple “template matching” algorithms
• STM – RANDOM ACCESS MEMORY (RAM) • on silicon chips • 100 Nano-second access time • usually volatile (lose information if power turned off)
• LTM – MAGNETIC DISKS • Floppy Disk, HDD, SSD
• LTM – OPTICAL DISKS • use lasers to read and sometimes write • more robust than magnetic media
• PDAs • often use RAM for their main memory
• FLASH MEMORY • used in PDAs, cameras etc. • silicon based but persistent • plug-in USB devices for data transfer