USB, Firewire, Bluetooth, and PS2 Ports

• Firewire is IEEE 1394.
• USB 1.2 and 2.0. Are 12 mbs and 480 mbs respectively (1.5 mBs and 60 mBs). b-bits B-Bytes. Making usb 2.0 40 times as fast as usb 1.2. Firewire is 400 mb/sec. 50 mBps. Its mBps is rating is lower but Firewire is actually faster than usb. I don't remember why.
• USB type 1.1, 3 meters maximum cable length.. Ver 2.0, 5 meters.
• Ports on a system board can be direct-solder (the port is mounted right on the system board and soldered to it) or the port can be screwed to the computer case and a wire from the port will link to a header that is soldered on the system board. You’ve seen these headers. No? The trend is toward direct-solder.
• Port types:  PS2 keyboard, mouse. Both use 6-pin mini DIN. Mouse is green, keyboard purple. The Purple Keyboard of Cairo. How Green is my Mouse. Older keyboards and mice used an “AT”  connector which was a larger 5-pin DIN.
• USB plug types. There ares 2 subtypes of type A usb plugs, regular type A and mini type A, and 3 subtypes of type B, standard B, mini-B, and alternate mini-B. There are matching type A, B, and C receptacles,
• USB: Consoles and hubs both have type A receptacles. Peripherals have type B receptacles. Thus a cable will have a type A plug on one end and a type B plug on the other. Hubs also have type B receptacles (as well as type A) - so that you can connect them to a console. USB cables with the same plug on each end are in violation of the USB spec.
• Any Bluetooth enabled device, almost everywhere in the world, can connect to other Bluetooth enabled devices located near it. Short range ad hoc networks called “piconets.” Connection established dynamically and automatically when they are in range. Simultaneous data and voice.
• Radio type and version type are 2 different things. Radio type controls radio power and distance, version type controls data transmission speed.
• Older bluetooth is 700kbps. 87.5 kBps. Newer specs are 1 Mbps for version 4, which is Bluetooth low energy technology (that is 1024 kbps.) 1 Mbps for version 1.2 (older version). Up to 3 Mbps supported for version 2.0, the Enhanced Data Rate version. There is also a version 2.1 EDR version. Up to 24 Mbps supported for Version 3.0, the  High Speed version.
• Unlike other wireless standards, the Bluetooth Core Specification provides product developers both link layer and application layer definitions, which support data and voice applications.
• 2.4 to 2.485 GHz, using a spread spectrum, frequency hopping, full-duplex signal at a nominal rate of 1600 hops/sec. The 2.4 GHz ISM band is available and unlicensed in most countries. Industrial, scientific, medical band.
• Class 3 radios – have a range of up to 1 meter
• Class 2 radios – most commonly found in mobile devices – have a range of 10 meters Class 1 radios – used primarily in industrial use cases – have a range of 100 meters
• BT “low energy technology” has a range of up to 200 meters.
• Low energy technology optimized for devices requiring maximum battery life instead of a high data transfer rate, consumes between 1/2 and 1/100 the power of classic Bluetooth technology.

Misc connectors

• DE-9,  DB-25 used for serial. Or DE-9 to DE-9. Female to male. Null modem uses same but different male-female (female on both ends of cable). Also pinouts are different.
• See D-sub list on page 70. D-subminiature – a long time ago. Second letter is for shell size, that is, the number of pins supported. Number is the actual number of pins. A=15, B=25, C=37, D=50, E=9. Followed by P or S for plug or socket.
• Possibly because the original PC used DB25 connectors for the serial and parallel ports, many people… not knowing the significance of the letter “B” … began to call all D-sub connectors “DB” connectors instead of specifying “DA,” “DC” or “DE.” When the PC serial port began to use 9-pin connectors, they were often called “DB9” instead of DE9. It is now common to see DE9 connectors [labeled as being]… “DB9” connectors. DB-9 is nearly always intended to be a 9 pin connector with an E size shell.
• However there are now D-sub connectors which have the original shell sizes, but more pins, and the names follow the same pattern. For example, the DE15, usually found in VGA cables, has 15 pins, in three rows, in an E size shell (9-pin shell). The full list of connectors with this pin spacing is: DE15, DA26, DB44, DC62, and DD78. Alternatively, following the same confusion mentioned above in which all D-sub connectors are called “DB”, these connectors are often called DB15HD, DB26HD, DB44HD, DB62HD, and DB78HD, where the “HD” stands for “high density”. They all have 3 rows of pins, except the DD78, which has 4.
• Case fans: rear exhaust, front intake.  Power supply connector or connect to motherboard w 2, 3 or 3 pins.
• Power supply connectors, ATX voltages are: +3.3, +5 (and +5 standby), -5 (optional), +12, -12. Older AT style supplies did not have a 3.3 volt pin.
• SATA, PATA hard driver interfaces. PATA also called ATA, IDE, and EIDE. ATA 1-8. For ATA-5 and later (which is ultraDMA/66), 80-wire cables are needed, instead of 40-wire. Connectors are the same. 40-pin. ATA-7 supports ultra DMA/133 (direct memory access). Also called Ultra ATA.
• ATA/133 ribbon cable has 80 wires. Earlier cable had 40. Same 40-pin connectors. ATA/133 drive will transfer data at only 33mBps instead of 133, if you use the older cable.