PC PORTS

PC Ports

Parallel ports:

25 Pin female, "D" connector
Sends and receives 8 bits of data at a time
Sends data synchronously

Serial ports:

25 Pin male, "D" connector or 9 Pin male, "D" connector
Sends and receives 1 bit of data at a time
Sends data asynchronously

Keyboard:

Key boards come with two types of connectors. They are:
1. DIN-5, DIN-5 has 5 pins and used with AT style keyboards.
2. Mini DIN-6, also known as PS/2 connector, has around port with 6 pins, one of which being a square pin used for alignment.
DIN-5 or PS2
Serial Interfaces: Mouse:
COM1, COM2 on a computer uses serial cable. The pin assignments are shown below. The computer acts as a DTE(Data Terminal Equipment) and the Modem acts as DCE (Data Communication Equipment).
Normally, a DTE device connects to a DCE device. If you want to connect two DTR devices, as you would do to hook up two computers via the serial line to exchange files, the cable itself must have cross connections. Such a cable is called null modem cable
Signal Name DB9 Pin
RX Received Data 2
TX Transmitted Data 3
DTR Data Terminal Ready 4
GND Ground 5
DSR Data Set Ready 6
RTS Request to Send 7
CTS Clear to send 8

9 Pin serial or PS2
Video:
HDA= 15 pin female, 3 rows of pins. (Current VGA and SVGA only)
COM Ports

COM1 and COM3 use IRQ4.
COM2 and COM4 use IRQ3.
The majority of PC's have only 2 COM port connectors.
Some important acronyms:
• ISA is an acronym for Industry Standard Architecture,
• EISA is a acronym for Extended Industry Standard Architecture,
• PCI is an acronym for Peripheral Component Interconnect, and
• MCA stands for Micro Channel Architecture.
• CPU stands for Central Processing Unit.
• SCSI stands for Small Computers Systems Interface. It is pronounced as Skuzzy.
• DIMM stands for Dual-Inline Memory Module
• SIMM stands for Single-Inline Memory Module
• SRAM - Static random access memory - Uses transistors to store information
• DRAM - Dynamic random access memory - Need to be refreshed to retain data.
• ROM - Read only memory - Data in ROM can not be erased or changed
• PROM - Programmable ROM - Once programmed, data can't be erased or changed
• EPROM - Erasable PROM - Data can be erased by ultraviolet light and can be reprogrammed using a programmer.
• EEPROM - Electronically erasable PROM - Data can be erased electrically. Chip can then be reprogrammed. EEPROMs are frequently used to store BIOS.
2. RAM stands for Random Access Memory. There are basically two types of RAM:
1. DRAM - Dynamic RAM, and


2. SRAM - Static RAM.
SRAM, being expensive, usually used for Cache memory. DRAM, being cheaper, is used for main memory.

3. PC Memory cards:
• A SIMM has a single row of 72 contact fingers, each making contact on both sides (Same pin number present on both sides of the card). An older version of SIMM card contain 30pins, and were used in 386 and some 486 machines.
• A DIMM (Dual-Inline Memory Module)has two rows of connecting fingers, one row on each side, and the total number of contacts are 168 contacts.
4. Monitor Connectors:
• If you are using a Monochrome / CGA/ EGA monitor, it is a digital monitor and will have a DB-9 Male connector that plugs into a digital adapter.
• If you are using a VGA/ SVGA monitor, it will have a male DB-15 connector that plugs into an analog adapter. You should never interchange an analog monitor to that of a digital adapter and vice versa, or severe damage may take place.
5. The storage capacity of various types of floppy:
Size------Type----Storage
5 1/4" ---DSHD----1.2MB
3 1/2" ---DSDD----720KB
3 1/2" ---DSHD----1.44MB
3 1/2" ---DSED----2.88MB
DSDD: Double Sided Double Density
DSHD: Double Sided High Density
DSED: Double Sided Extra Density