QUICK GUIDE TO COMPUTER CABLES
by Bill Becwar
LEGAL STUFF - This guide is as complete and accurate as I can make it, however, I can't be responsible for errors, omissions, typing mistakes, bad downloads, or your dog biting you. I know that somebody, somewhere is going to cross a wire. Best advice if you want to build one of these cables: Complete the wiring all in one work session. Then check the connections, preferably with an ohmmeter. Go away for a while and do something else, then return and CHECK the connections again. If you have any comments or find any errors, leave E-Mail to William Becwar on EXEC-PC, the largest and finest BBS in the country, (414) 789-4210, or on CompuServe 72060,251. Good Luck!
POWER SUPPLY CONNECTORS -
Typical Power Supply has 6 Connectors: 2 ea. - 6 pin for
Motherboard Power and 4 ea. - 4 pin for Disk Drive Power.
Motherboard Power Connectors
P8 P9 Pin Signal Pin Signal
—————————– —————————
1 - Power Good 1 - GND 2 - +5v (or N.C.) 2 - GND 3 - +12v 3 - -5v 4 - -12v 4 - +5v 5 - GND 5 - +5v 6 - GND 6 - +5v
Disk Drive Power Connectors (4 - 4 pin)
Pin Signal
—————————–
1 - +12v 2 - GND 3 - GND 4 - +5v
MOTHERBOARD CONNECTORS -
Motherboards have various combinations of connectors depending
on design type and built-in facilities. These will be found in a typical clone.
Backup Battery Connector (AT only)
Pin Signal
—————————–
1 - Batt+ 2 - [KEY] 3 - GND 4 - GND
LED Power and Key Lock (AT only)
Pin Signal
—————————–
1 - LED power 2 - GND 3 - GND 4 - Key Switch 5 - GND
Speaker Connector
Pin Signal
—————————–
1 - -Speaker 2 - [KEY] 3 - GND 4 - +Speaker +5v
Turbo Indicator Connector
Used only on Turbo switchable machines. Safest Connector on
the machines that have it; can't be connected backwards!
Pin Signal
—————————–
1 - +5v 2 - *HIGH SPEED 3 - +5v
MOTHERBOARD I/O CARD EXPANSION SLOTS
Not exactly for cabling, but a good reference anyway.
8-bit slots (PC/XT/AT)
COMPONENT SIDE NON-COMPONENT SIDE
Pin Signal Pin Signal ————— ————— A1 -I/O CH CLK B1 GND A2 SD7 B2 RESET DRV A3 SD6 B3 +5v A4 SD5 B4 IRQ 9 A5 SD4 B5 -5v A6 SD3 B6 DRQ 2 A7 SD2 B7 -12v A8 SD1 B8 Reserved / OWS A9 SD0 B9 +12v A10 -I/O CH RDY B10 GND A11 AEN B11 -SMEMW A12 SA19 B12 -SMEMR A13 SA18 B13 -IOW A14 SA17 B14 -IOR A15 SA16 B15 -DACK3 A16 SA15 B16 DRQ3 A17 SA14 B17 -DACK1 A18 SA13 B18 DRQ1 A19 SA12 B19 -REFRESH A20 SA11 B20 CLK A21 SA10 B21 IRQ7 A22 SA9 B22 IRQ6 A23 SA8 B23 IRQ5 A24 SA7 B24 IRQ4 A25 SA6 B25 IRQ3 A26 SA5 B26 -DACK2 A27 SA4 B27 T/C A28 SA3 B28 BALE A29 SA2 B29 +5v A30 SA1 B30 OSC A31 SA0 B31 GND
Motherbaord Expansion slots continued…
16-bit Slots (AT only)
COMPONENT SIDE NON-COMPONENT SIDE
Pin Signal Pin Signal ————— ————— C1 SBHE D1 -MEM CS16 C2 LA23 D2 -I/O CS16 C3 LA22 D3 IRQ10 C4 LA21 D4 IRQ11 C5 LA20 D5 IRQ12 C6 LA19 D6 IRQ13 C7 LA18 D7 IRQ14 C8 LA17 D8 -DACK0 C9 -MEMR D9 DRQ0 C10 -MEMW D10 -DACK5 C11 SD08 D11 DRQ5 C12 SD09 D12 -DACK6 C13 SD10 D13 DRQ6 C14 SD11 D14 -DACK7 C15 SD12 D15 DRQ7 C16 SD13 D16 +5v C17 SD14 D17 -MASTER C18 SD15 D18 GND
Keyboard Connector
Pin Signal
—————————–
1 - KBD CLK OUT 2 - KBD SERIAL OUT 3 - KBD RESET IN 4 - KBD GND 5 - KBD +5v
FLOPPY DISK CABLES -
Floppy / Hard Drive Power Connectors
Pin Signal
—————————–
1 - +12v 2 - GND 3 - GND 4 - +5v
Floppy Disk Drive Interface Cable
Pin Signal Pin Signal
————————————————————-
1 - GND 2 - N/C 3 - GND 4 - N/C 5 - GND 6 - N/C 7 - GND 8 - Index 9 - GND 10 - Motor Enable A 11 - GND 12 - Drive Select B 13 - GND 14 - Drive Select A 15 - GND 16 - Motor Enable B 17 - GND 18 - Stepper Direction 19 - GND 20 - Step Pulse 21 - GND 22 - Write Data 23 - GND 24 - Write Enable 25 - GND 26 - Track 0 27 - GND 28 - Write Protect 29 - GND 30 - Read Data 31 - GND 32 - Select Head 1 33 - GND 34 - (Spare)
HARD DISK CABLES -
ST-506 Hard Disk Drive Control/Data Cables
Floppy / Hard Drive Power Connectors
Pin Signal
—————————–
1 - +12v 2 - GND 3 - GND 4 - +5v
ST-506 Control Cable
Pin Signal Pin Signal
————————————————————-
1 - Head Select 8 2 - GND 3 - Head Select 4 4 - GND 5 - Write Gate 6 - GND 7 - Seek Complete 8 - GND 9 - Track 0 10 - GND 11 - Write Default 12 - GND 13 - Head Select 1 14 - GND 15 - Reserved 16 - GND 17 - Head Select 2 18 - GND 19 - Index 20 - GND 21 - Ready 22 - GND 23 - Step 24 - GND 25 - Drive Select 1 26 - GND 27 - Drive Select 2 28 - GND 29 - Drive Select 3 30 - GND 31 - Drive Select 4 32 - GND 33 - Direction In 34 - GND
ST-506 Data Cable
Pin Signal Pin Signal
————————————————————-
1 - Drive Selected 2 - GND 3 - Reserved 4 - GND 5 - Reserved 6 - GND 7 - Reserved 8 - GND 9 - Reserved 10 - GND 11 - GND 12 - GND 13 - MFM Write Data+ 14 - MFM Write Data- 15 - GND 16 - GND 17 - MFM Read Data+ 18 - MFM Read Data- 19 - GND 20 - GND
ESDI Hard Disk Drive Control/Data Cables
ESDI Control Cable
Pin Signal Pin Signal
————————————————————-
1 - Head Select 3 2 - GND 3 - Head Select 2 4 - GND 5 - Write Gate 6 - GND 7 - Config/Status Data 8 - GND 9 - Transfer Ack. 10 - GND 11 - Attention 12 - GND 13 - Head Select 0 14 - GND 15 - Sec/Addr Mark Find 16 - GND 17 - Head Select 1 18 - GND 19 - Index 20 - GND 21 - Ready 22 - GND 23 - Transfer Request 24 - GND 25 - Drive Select 1 26 - GND 27 - Drive Select 2 28 - GND 29 - Drive Select 3 30 - GND 31 - Read Gate 32 - GND 33 - Command Data 34 - GND
ESDI Data Cable
Pin Signal Pin Signal
————————————————————-
1 - Drive Selected 2 - Sec/Addr Mark Found 3 - Seek Completed 4 - Address Mark Enable 5 - Reserved/Step Mode 6 - GND 7 - Write Clock+ 8 - Write Clock- 9 - Cartridge Changed 10 - Read Ref. Clock+ 11 - Read Ref. Clock- 12 - GND 13 - NRZ Write Data+ 14 - NRZ Write Data- 15 - GND 16 - GND 17 - NRZ Read Data+ 18 - NRZ Read Data- 19 - GND 20 - Index
SCSI Hard Disk Drive Interface Cable
Pin Signal Pin Signal
————————————————————-
1 - GND 2 - Data Line 0 3 - GND 4 - Data Line 1 5 - GND 6 - Data Line 2 7 - GND 8 - Data Line 3 9 - GND 10 - Data Line 4 11 - GND 12 - Data Line 5 13 - GND 14 - Data Line 6 15 - GND 16 - Data Line 7 17 - GND 18 - Data Parity Line 19 - GND 20 - GND 21 - GND 22 - GND 23 - GND 24 - GND 25 - N/C 26 - Terminator Power 27 - GND 28 - GND 29 - GND 30 - GND 31 - GND 32 - Attention 33 - GND 34 - GND 35 - GND 36 - Busy 37 - GND 38 - Acknowledge 39 - GND 40 - Reset 41 - GND 42 - Message 43 - GND 44 - Select 45 - GND 46 - C/D 47 - GND 48 - Request 49 - GND 50 - I/O
DISPLAY ADAPTOR CONNECTORS -
Monochrome (MDA), Hercules, Color (CGA) Adaptors
Connector type - DB-9
Pin Signal Pin Signal
——————————————————————-
1 GND 6 Intensity 2 GND 7 Video * 3 N/C or RED 8 Horizontal Drive 4 N/C or GREEN 9 Vertical Drive 5 N/C or BLUE
- NTSC Video on some clone boards
EGA Adaptor
Connector Type - DB-9
Pin Signal Pin Signal
——————————————————————-
1 GND 6 Secondary Green / Intensity 2 Secondary Red 7 Secondary Blue / Mono Video 3 Primary Red 8 Horizontal Drive 4 Primary Green 9 Vertical Drive 5 Primary Blue
VGA Adaptor
Connector Type - DB-15
Pin Signal Pin Signal
——————————————————————-
1 Red Video 9 [KEY] 2 Green Video 10 Sync GND 3 Blue Video 11 Monitor ID - Bit 1 4 - Monitor ID - Bit 2 12 Monitor ID - Bit 0 5 - GND 13 Horizontal Sync 6 - Red GND 14 Vertical Sync 7 - Green GND 15 N/C (Reserved) 8 - Blue GND
PARALLEL PRINTER PORT
I/O Mapping
————————–
LPT1: $378-37A LPT2: $278-27A
DB-25 Connector (Computer End)
Pin Signal Pin Signal
——————————————————————-
1 *STROBE 14 *Auto Feed 2 Data Bit 0 15 *Error 3 Data Bit 1 16 *Initialize Printer 4 Data Bit 2 17 *Select Input 5 Data Bit 3 18 GND 6 Data Bit 4 19 GND 7 Data Bit 5 20 GND 8 Data Bit 6 21 GND 9 Data Bit 7 22 GND 10 *Acknowledge 23 GND 11 Busy 24 GND 12 Paper Out 25 GND 13 Select
Centronics 36 pin Connector (Printer End)
Pin Signal Pin Signal
——————————————————————-
1 *STROBE 19 GND
2 Data Bit 0 20 GND
3 Data Bit 1 21 GND
4 Data Bit 2 22 GND
5 Data Bit 3 23 GND
6 Data Bit 4 24 GND
7 Data Bit 5 25 GND
8 Data Bit 6 26 GND
9 Data Bit 7 27 GND
10 *Acknowledge 28 GND
11 Busy 29 GND
12 Paper Out 30 GND
13 Select 31 *Prime
14 *Auto Feed XT 32 *Error
15 {OSCXT} 33 Signal GND
16 Signal GND 34 N/C
17 Frame GND 35 N/C
18 +5v 36 N/C
SERIAL PORTS
NOTE: The IBM PC uses a DTE (Data Terminal Equipment) Connection standard. Most Modems are DCE (Data Communication Equipment).
I/O Map
—————————–
COM1: $3F8-3FF COM2: $2F8-2FF COM3: $3E8-3EF COM4: $2E8-2EF
DB-9 Connector
Pin Signal Pin Signal
——————————————————————-
1 CD Carrier Detect 6 DSR Data Set Ready 2 RXD Receive Data 7 RTS Request to Send 3 TXD Transmit Data 8 CTS Clear to Send 4 DTR Data Term. Ready 9 RI Ring Indicator 5 GND Signal GND
DB-25 Connector
Pin Signal Pin Signal
——————————————————————-
1 GND Ground / Shield 14 {2nd TXD}
2 TXD Transmit Data 15 Transmit Clock
3 RXD Received Data 16 {2nd Rec. Clock}
4 RTS Request to Send 17 {Receive Clock}
5 CTS Clear to Send 18 {Unassigned}
6 DSR Data Set Ready 19 {2nd RTS}
7 GND Ground 20 DTR Data Term Ready
8 DCD Carrier Detect 21 {Sig. Quality}
9 {Reserved} 22 RI Ring Indicator
10 {Reserved} 23 {Data Rate Sel.}
11 {Unassigned} 24 {Transmit Clock}
12 {2nd CD} 25 {Unassigned}
13 {2nd CTS}
NULL MODEM CONNECTION-
RS-232 Definition Computer/Terminal Modem
Signal DTE DCE
9-pin 25-pin 25-pin
——————————————————————- GND Signal GND 5 1 1 TXD Transmit Data 3 2 3 RXD Receive Data 2 3 2 RTS Req. to Send 7 4 5 CTS Clear to Send 8 5 4 DSR Data Set Ready 6 6 20 GND Chassis GND - 7 7 CD Carrier Detect 1 8 8 DTR Data Term. Ready 4 20 6
DTE DCE
1 þÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄþ 1
2 þÄÄÄÄÄÄÄÄÄÄ¿ ÚÄÄÄÄþ 2
ÚÄÄÄÄþ³þÄÄÄÄÙ
3 þÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄþ 3
4 þÄÄÄÄÄÄÄÄÄÄ¿ ÚÄÄÄÄþ 4
ÚÄÄÄÄþ³þÄÄÄÄÙ
5 þÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄþ 5
6 þÄÄÄÄÄÄÄÄÄÄ¿ ÚÄÄÄÄþ 6
³ ³
7 þÄÄÄÄÄÄÄÄÄþ³þÄÄÄþ³þÄÄÄþ 7
ÚÄÄÄÄþ³þÄÄÄÄÙ
8 þÄÄÄþ³þÄÄÄþ³þÄÄÄÄÄÄÄÄÄþ 8
³ ³
20 þÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄþ 20
GAME CONNECTOR
DB-15 Connector
Pin Signal Pin Signal
——————————————————————-
1 +5v 9 +5v 2 Button 1-1 10 Button 2-1 3 X1 11 X2 4 GND 12 GND 5 GND 13 Y2 6 Y1 14 Button 2-2 7 Button 1-2 15 N/C 8 N/C
Buttons - Connect from GND to Button inputs X and Y pots connect from +5v to X-Y inputs.
JOYSTICK CONNECTOR
DB-9 Connector
Pin Signal Pin Signal
——————————————————————-
1 JOY0 6 Fire Button 2 JOY1 7 +5v 3 JOY2 8 GND 4 JOY3 9 POT X 5 POT Y