I found this site, dunno if its been posted before. but useful for finding out what all the wires mean!
http://www.pccables.com/cabtech.htm
for the lazy:
Serial Adapters
DB-9 to DB-25 Adapter or Cable
Used to adapt serial ports to the proper size
25 Pin 9 Pin Signal-RS232
Connector Connector
1 n/a Protective Ground
2 3 TX Transmit
3 2 RX Recieve
4 7 RTS Request to Send
5 8 CTS Clear to Send
6 6 DSR Data set Ready
7 5 Signal Ground
8 1 DCD Data carrier detect
9 n/a + Transmit
11 n/a - Transmit
18 n/a + Recieve
20 4 DTR Data terminal ready
22 9 RI Ring Indicator
23 n/a DSRD Data signal-rate indicator
25 n/a - Recieve
DB-9 to DB-25 Adapter
Opposite of Above
TEST Adapters
Serial Port Loopback (9 Pin)
Used to verify that a port is working.
9 PIN D-SUB FEMALE
Name Pin Pin Name
DCD 1 6 DSR
DCD 1 9 RI
RXD 2 3 TXD
DTR 4 6 DSR
RTS 7 8 CTS
Serial Port Loopback (25 Pin)
Used to verify that a port is working.
25 PIN D-SUB FEMALE
Name Pin Pin
1 7
2 3
4 5,8
6 11,20,22
15 17,23
18 25
Parallel Port Loopback (IBM, Checkit and Most Others)
Used to verify that a Printer port is working.
Name Pin Pin Name
Strobe 1 13 Select
Data Bit0 2 15 Error
Acknowledge 10 16 Input Prime
Busy 11 17 Select In
Paper Out 12 14 Auto Feed XT
Parallel Port Loopback (Norton)
Used to verify that a port is working. Norton Utilities: Norton Diagnostics
Name Pin Pin Name
Data Bit 0 2 15 Error
Data Bit 1 3 13 Select
Data Bit 2 4 12 Paper Out
Data Bit 3 5 10 Acknowledge
Data Bit 4 6 11 Busy
Power Cables
Power Supply to Motherboard AT P8-P9
Pin# Color Function
1 Orange Power Good
2 Red +5V DC
3 Yellow +12V DC
4 Blue -12V DC
5 Black Ground
6 Black Ground
7 Black Ground
8 Black Ground
9 White -5V DC
10 Red +5V DC
11 Red +5V DC
12 Red +5V DC
Power Supply to Motherboard ATX
Pin# Color Function
1 Orange +3.3V DC
2 Orange +3.3V DC
3 Black Ground
4 Red +5V DC
5 Black Ground
6 Red +5V DC
7 Black Ground
8 Gray Power OK
9 Purple +5V standby
10 Yellow +12V DC
(11) Orange(22) +3.3V DC
(11) Brown(22) 3.3V sense
12 Blue -12V DC
13 Black Ground
14 Green PS-ON
15 Black Ground
16 Black Ground
17 Black Ground
18 White -5V DC
19 Red +5V DC
20 Red +5V DC
Power Supply plug 5.25-inch 4-pin Molex
Pin# Color Function
1 Yellow +12V DC
2 Black Ground
3 Black Ground
4 Red +5V DC
Power supply plug 3.5-inch
Pin# Color Function
1 Yellow +12V DC
2 Black Ground
3 Black Ground
4 Red +5V DC
Monitor Reference
Hercules/Monochrome Adapter
Pin# Label Function
1 GND Ground
2 GND Ground
3 N.C. Not Connected
4 N.C. Not Connected
5 N.C. Not Connected
6 INTENSITY Intensity
7 VIDEO TTL video signal
8 H-SYNC Horizontal Synch (18.432KHz)
9 V-SYNC Vertical Synch (50Hz)
CGA Color Graphics Display Adapter
Pin# Label Function
1 GND Ground
2 GND Ground
3 RED Red color signal
4 GREEN Green color signal
5 BLUE Blue color signal
6 INTENSITY + Intensity
7 RES Reserved
8 H-SYNC Horizontal Synch
9 V-SYNC Vertical Synch
CGA Composite Video Used on Commodore systems old Apples
Pin# Label Function
1(pin) 1.5 Volt Dc Video Signal
2(shell) GND Ground
EGA Enhanced Graphics Adapter
Pin# Label Function
1 GND Ground
2 RED2 Secondary Red color signal
3 RED Red color signal
4 GREEN Green color signal
5 BLUE Blue color signal
6 GREEN2 Secondary Green color signal + Intensity
7 BLUE2 Secondary Blue color signal + Monochrome
8 H-SYNC Horizontal Synch
9 V-SYNC Vertical Synch
Color VGA Adapter
Pin# Label Function
1 RED Red color signal
2 GREEN Green color signal
3 BLUE Blue color signal
4 ID2 Monitor identification bit 2
5 N.C. Not Connected
6 GND-RED Ground Red signal
7 GND-GREEN Ground Green signal
8 GND-BLUE Ground Blue signal
9 N.C. Not Connected
10 GND-SYNC Ground Sync signal
11 ID1 Monitor identification bit 1
12 ID0 Monitor identification bit 0
13 H-SYNC Horizontal Synchronization
14 V-SYNC Vertical Synchronization
15 N.C. Not connected
Ribbon Cables
EIDE IDE 40 Pin Cable
Pin# Signal Description Function
1 RESET Reset
2 GND Ground
3 DD7 Data Line 7
4 DD8 Data Line 8
5 DD6 Data Line 6
6 DD9 Data Line 9
7 DD5 Data Line 5
8 DD10 Data Line 10
9 DD4 Data Line 4
10 DD11 Data Line 11
11 DD3 Data Line 3
12 DD12 Data Line 12
13 DD2 Data Line 2
14 DD13 Data Line 13
15 DD1 Data Line 1
16 DD14 Data Line 14
17 DD0 Data Line 0
18 DD15 Data Line 15
19 GND Ground
20 Select Selection for Pin 20
21 DMARQ DMA Request (optional)
22 GND Ground
23 DIOW
24 GND Ground
25 DIOR
26 GND Ground
27 IORDY IDE device still busy (optional)
28 Reserved Used for Cable Select
29 DMACK DMA Acknowledge (optional)
30 GND Ground
31 INTRQ Interupt Request
32 IOCS16 16 Bit data transfer
33 DA1 Bit 1 Address bus, for addressing the
Internal data register on the hard drive
34 PDIAG Passed Diag Hard Drive self test concluded
35 DA0 Bit 0 Address bus
36 DA2 Bit 2 Address bus
37 CS0 Selection Command Block Register
38 CS1 Selection Command Block Register
39 DA/SP Drive Active Hard drive is active / after slave drive
Communicates its presence
40 GND Ground
Linear Mode
