Input/Output Devices Common and Specialty

Serial Ports

UARTs Universal Asynchronous Receiver/Transmitter Converts between parallel (bus) and serial Connects the computer to a 9-pin, or 25- pin serial port – an RS-232 connector

Terminal Emulation “Big Iron” computer systems use terminals and can use computers VT100 is old, standard terminal used by lots of equipment (Cisco ) Terminal Emulation software (once included with modems) about dead but not completely gone

USB Universal Serial Bus – 4 wires USB 1.1 supports 1.5Mbps and 12Mbps USB 2.0 supports transfer rates of 480Mbps (about 60MBps) – 25 times faster than parallel ports USB 3.0 supports up to 5Gbps Far more common than its cousin: IEEE 1394 or Firewire 1996 for USB1.0; 2000 for USB 2.0; 2003 for USB 2.0 in laptops

Every device shares The USB bus with Every other device On the Host; bus slows And power consumed

Device Manager, Expand USB, Right-click Hub Properties

USB issues Powered, and unpowered, devices can overload Host Controller Three speeds: –Low-Speed (USB 1.1) = 1.5 Mbps –Full-Speed (USB 1.1) = 12 Mbps –Hi-Speed (USB 2.0) = 480 Mbps –SuperSpeed (USB 3.0) = -> 4.8 Gbps Hi-Speed is backwards compatible as is SuperSpeed

USB Hubs Host Controller supports up to 127 devices Use a hub when you run out of ports Powered (or not) Can daisy-chain up to five hubs Allows longer cable runs to devices Theory is 5m for longest cable; I have found ~20-foot cables at Fry’s

USB Configuration Install the device driver first, then plug in the device Windows 2k and XP support keyboards, mice and most flash drives Make sure you have the speed the device can run at, otherwise it will default down in speed Make sure you have enough power (powered hub(s))

Firewire IEEE 1394 Older (by six months) than USB Digital Video Camcorders and (older) Apple computers 6-pin powered connector, or a 4-pin bus- powered connector 1394a at 400 Mbps; 1394b at 800 Mbps Devices can bus master – talk to each other Maximum of 63 devices Hubbed or daisy-chained devices Max cable length is 4.5m

More Firewire Can daisy-chain devices (without hubs) if you wish; USB requires hub(s) Should install driver first, but most external hard disk drives and Digital Video are supported by Windows

Legacy Free PC No serial port(s) No parallel port No keyboard/mouse ports No floppy drive connector Thus, no Super I/O chip

Port Issues Is it the port, or is it the device? Has the CMOS been told to turn off the port? Or Device Manager? Is the port broken from too much use? –Bent or broken pins on connector –Bent or broken shell around pins

Somebody got really upset at USB port or device!

Keyboards – 1 Oldest form of input and still primary form If you want to use a USB keyboard, make sure BIOS knows about it (Enable “USB Keyboard Support” somewhere)

Keyboards – 2 Spills can cook the keyboard controller (Super I/O chip) on motherboard Physical damage –rage or a dropped book Dirt (and bits of that sandwich) I use foaming bathroom cleaner sparingly to clean keyboards Need a really good reason to repair a keyboard

Mice Windows 98 will grind to a halt if it does not detect a mouse; 2000 and XP won’t Windows has drivers for most mouse functions – extra buttons require extra drivers Mechanical or ball mouse needs cleaning at points of contact with internal rollers Take a tour through Mouse Control Panel applet

Ball Mouse Gunk Y axis X axis Spring loaded wheel

Scanners Scanners take a PICTURE of the object – you can read the text but computer can not without additional software Control of scanner is either at the scanner or software installed on computer – use one or the other but not both at the same time TWAIN – Technology Without An Interesting Name OCR – Optical Character Recognition Scan’s file size can quickly get out of hand

Buying a Scanner Most people simply go on price – whatever sells for $50-$125. More dollars equals more control over scan parameters. Optical resolution – how many data points in an inch. Mine is 9600x4800 Color depth – how much information can be stored for each data point. 48-bit for me Connection – USB now, thank you! Was parallel port

Biometric Devices Keep your computer secure Mostly fingerprint scanning to replace username and password(s) Voice recognition – the illusive dream; it is getting better, but still a long way from accurate Make it work: –Install the device –Register your identity with device “train it” –Set what to do when it recognizes you

Barcode Readers Used for inventory control – track in and out Make sure to use the device the software will understand – forget price More USB ports

Touch Screens Replaces mouse – uses stylus or finger as replacement for mouse click Built-in screens like the one at the checkout counter at Vons, or Standalone monitors (HP used to make one)

KVM Switches Keyboard, Video and Mouse Allows multiple computers and single keyboard/mouse/monitor Don’t cross the cables!

Digital Cameras Read reviews – MacWorld or a PC magazine or web Removable storage media – the “film” usually Secure Digital (SD) cards Storage data – measured in megapixels, 3 to 12 megapixels today Zoom with camera’s optics not software

Webcams Resolution, like cameras, in megapixels – 1.3 per Michael Frame rate – pictures per second – up to around 30 per second More USB connections Configuring webcams – follow the software’s instructions Good luck with applications!