I thought this excellent guide to PC Cables needed a slight update. The original work is contained in the CABLES1.TXT file by Bill Becwar and is included in this ZIP file in its entire, unaltered state. Below I have included the layouts to the cables I have worked with recently that might be of help to others. Taking the disclamer from Bill Becwar, I repeat it below to prevent any thought that I may be held liable for any problems this guide may or may not cause you or anyone else. ----- 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 Darrell Bivens on Silver Bullet BBS, (615) 337-9683 Sweetwater, East Tennessee. Good Luck! ----- Null modem cables (Several variations) The first variation is explained in an excert from the ZIP162 DOC file. The ZIP program will allow computer <> computer file transfers through a null modem cable. It can even clone itself over the cable (in case the disk drives are not compatible/working). I have tried this cable with Central Point Software's DriveMap 1.0 program and Lap Link V 5.0. It works perfectly. Also note if you build a 25 <> 25 pin cable and you need to connect to a 9 pin COM port that a STANDARD 9F > 25M adapter and/or adapter cable will connect the correct pins. I have not tried a 9 <> 9 pin cable using a 25F > 9M adapter. It may or may not work. I don't have an cable of this type to check. Excert from ZIP162.DOC file: "----------------------- C. APPROPRIATE SERIAL CABLES ------------------------ SERIAL NULL MODEM CABLES, in various combinations of 9- and 25-pin connectors, are available from a wide variety of sources, and a simple cable in the configuration you need (for example, DB9 to DB25 female) should cost less than $10 at Radio Shack or many computer stores. Double-headed null modem cables (both 9 and 25 pin on each end) are also made, and would be ideal for use with ZIP; I am told that a good source for these is: DALCO, 233 Pioneer Blvd, Springboro OH 45066; (800)445-5342 If you're building or shopping for a cable, you need a "null modem" cable, meaning the transmit and receive data lines should be crossed, and the signal ground connected straight through. (The pin numbers depend on whether you have a small DB9 or large DB25 connector, see figure.) No other connections should be needed; ZIP uses no hardware handshaking lines. (NOTE: ZIPDUP does require the DTR connections between pins 20/4 and 6.) |--COMPUTER 1--| |--COMPUTER 2--| DB9F or DB25F DB25F or DB9F pin 2 - - - - 3 - - - - - - - 2 - - - - 3 \ transmit & 3 - - - - 2 - - - - - - - 3 - - - - 2 / receive data 5 - - - - 7 - - - - - - - 7 - - - - 5 - signal ground pin 4 - - - - 20 - - - - - - 6 - - - - 6 * \ 6 - - - - 6 - - - - - - - 20 - - - 4 * \handshaking (optional) 7 - - - - 4 - - - - - - - 5 - - - - 8 /(* required for ZIPDUP) 8 - - - - 5 - - - - - - - 4 - - - - 7 / Actually, any serial cable that doesn't work by itself, should work with a "null modem adapter" attached. If available, use a well shielded cable; high speed transmissions can be especially susceptible to RF interference." ---------------------------------------------------------------------------- In talking around and asking several Tech. support persons I received some variations on the null modem cable. Below are the most to least common types 'believed' to work. (Using the chart layout from above) |--COMPUTER 1--| |--COMPUTER 2--| DB9F or DB25F DB25F or DB9F pin - - - - 1 - - - - - - - 1 - - - - 3 - - - - 2 - - - - - - - 3 - - - - 2 2 - - - - 3 - - - - - - - 2 - - - - 3 7 - - - - 4 - - - - - - - 5 - - - - 8 8 - - - - 5 - - - - - - - 4 - - - - 7 6 - - - - 6 - - - - - - - 20- - - - 4 (As you can see here, pins 1 - - - - 8 - - - - - - - 20- - - - 4 6 & 8 are jumped together 4 - - - - 20- - - - - - - 6 - - - - 6 and join the 20 on the 4 - - - - 20- - - - - - - 8 - - - - 1 other end (both ways)). |--COMPUTER 1--| |--COMPUTER 2--| DB9F or DB25F DB25F or DB9F pin - - - - 1 - - - - - - - 1 - - - - 3 - - - - 2 - - - - - - - 3 - - - - 2 2 - - - - 3 - - - - - - - 2 - - - - 3 8 - - - - 5 - - - - - - - 20- - - - 4 (As you can see here, pins 6 - - - - 6 - - - - - - - 20- - - - 4 5, 6 & 8 are jumped together 1 - - - - 8 - - - - - - - 20- - - - 4 and join the 20 on the 4 - - - - 20- - - - - - - 5 - - - - 8 other end (both ways)). 4 - - - - 20- - - - - - - 6 - - - - 6 4 - - - - 20- - - - - - - 8 - - - - 1 |--COMPUTER 1--| |--COMPUTER 2--| DB9F or DB25F DB25F or DB9F pin - - - - 1 - - - - - - - 1 - - - - 3 - - - - 2 - - - - - - - 3 - - - - 2 2 - - - - 3 - - - - - - - 2 - - - - 3 7 - - - - 4 - - - - - - - - - - - (4 & 5 jumpered on one end 8 - - - - 5 - - - - - - - - - - - but don't connect thru.) - - - - - - - - - - - 4 - - - - 7 (4 & 5 jumpered on one end - - - - - - - - - - - 5 - - - - 8 but don't connect thru.) 6 - - - - 6 - - - - - - - 20- - - - 4 4 - - - - 20- - - - - - - 6 - - - - 6 The above 9 pin connections were 'figured out' using the 9<>25 pin adapters with the following pinouts. This is the pin outs for adapters from<>to 9<>25 pin cables. |-- 9F <> 25M --| |-- 25F <> 9M --| DB9F or DB25M DB25F or DB9M pin 1 - - - - 8 - - - - - - - 1 - - - - 2 - - - - 3 - - - 3 - - - - 2 - - - - 3 - - - - 2 - - - 2 - - - - 3 - - - - 4 - - - - 20- - - 20- - - - 4 - - - - 5 - - - - 7 - - - 7 - - - - 5 - - - - 6 - - - - 6 - - - - - - - 6 - - - - 7 - - - - 4 - - - 4 - - - - 7 - - - - 8 - - - - 5 - - - - - - - 8 - - - - 9 - - - - 22- - - - - - - 9 - - - - Another strange cable I ran into was for a HP Plotter (also applies to the HP Paint Jet). A standard serial cable would not work, nor would a null modem cable. Before you go out and buy an expensive HP cable try making your own from one of the following pinouts. Type I (From a Commercially produced cable/computer store) |-- COMPUTER --| >>> |--HP Plotter--| (Or Paint Jet) *DB9F or DB25F >>> DB25M pin 3 - - - - 2 - - - - - - - 3 2 - - - - 3 - - - - - - - 2 8 - - - - 5 - - - - - - - 20 - - - - 6 - - - - - - - 20 5 - - - - 7 - - - - - - - 7 * The above 9 pin connections were 'figured out' using the 9<>25 pin adapters shown above. Type II (From a Commercially produced cable/computer store) |-- COMPUTER --| >>> |--HP Plotter--| (Or Paint Jet) DB9F or *DB25F >>> DB25M pin 1 - - - - - - - - - - - 4 2 - - - - 3 - - - - - - - 2 3 - - - - 2 - - - - - - - 3 4 - - - - 20- - - - - - - 5 4 - - - - 20- - - - - - - 6 5 - - - - 7 - - - - - - - 7 6 - - - - - - - - - - - 4 7 - - - - 4 - - - - - - - 8 8 - - - - - - - - - - - 20 * The above 25 pin connections were 'figured out' using the 9<>25 pin adapters shown above. Type III (From a Computer store made cable in use 12/6/93) |-- COMPUTER --| >>> |--HP Plotter--| (Or Paint Jet) *DB9F or DB25F >>> DB25M pin - - - - 1 - - - - - - - 1 3 - - - - 2 - - - - - - - 3 2 - - - - 3 - - - - - - - 2 8 - - - - 5 - - - - - - - 20 6 - - - - 6 - - - - - - - 20 5 - - - - 7 - - - - - - - 7 4 - - - - 20- - - - - - - 5 4 - - - - 20- - - - - - - 6 * The above 9 pin connections were 'figured out' using the 9<>25 pin adapters shown above. Type IV (From a Home made cable in use 12/6/93) |-- COMPUTER --| >>> |--HP Plotter--| (Or Paint Jet) DB9F or *DB25F >>> DB25M pin 1 - - - - - - - - - - - 1 2 - - - - 3 - - - - - - - 2 3 - - - - 2 - - - - - - - 3 4 - - - - 20- - - - - - - 5 4 - - - - 20- - - - - - - 6 5 - - - - 8 - - - - - - - 7 6 - - - - 6 - - - - - - - 20 8 - - - - 5 - - - - - - - 20 * The above 25 pin connections were 'figured out' using the 9<>25 pin adapters shown above. DOS V 6.0 (and Central Point Software's PCTools 8.0 w/ Drive Map 1.0) introduced the ability to use a parallel cable (Printer port to Printer port cable) to connect two PCs together and share drives. The pin outs for the "LINK DOS 6.0" cable follows: |--COMPUTER 1--| |--COMPUTER 2--| DB25M DB25M pin 2 - - - - - - - - - - - - 15 3 - - - - - - - - - - - - 13 4 - - - - - - - - - - - - 12 5 - - - - - - - - - - - - 10 6 - - - - - - - - - - - - 11 10- - - - - - - - - - - - 5 11- - - - - - - - - - - - 6 12- - - - - - - - - - - - 4 13- - - - - - - - - - - - 3 15- - - - - - - - - - - - 2 Most serial port connections only require a few wires to be connected. The most common types of connections only require: |-- COMPUTER --| |-- DEVICE --| *DB9F or DB25F DB25M or DB9F* pin - - - - 1 - - - - - - - 1 - - - - 3 - - - - 2 - - - - - - - 2 - - - - 3 2 - - - - 3 - - - - - - - 3 - - - - 2 7 - - - - 4 - - - - - - - 4 - - - - 7 8 - - - - 5 - - - - - - - 5 - - - - 8 6 - - - - 6 - - - - - - - 6 - - - - 6 5 - - - - 7 - - - - - - - 7 - - - - 5 1 - - - - 8 - - - - - - - 8 - - - - 1 4 - - - - 20- - - - - - - 20- - - - 4 * The above 9 pin connections were 'figured out' using the 9<>25 pin adapters shown above. Full pin 25M <> 25F cables have all pins connected straight through: 25F <> 25M 1 1 2 2 3 3 ... ... 23 23 24 24 25 25 thus making extension cables for either serial or printer cable connections. Serial cables that have both Male ends or both Female ends are strange. The pins are connected from<>to the same pin number on the other end (1-1, 2-2, 3-3, ... 25-25) but since the gender is the same on both ends these cables are not extension cables but actually CROSS the wires. If you were to plug two 'same gender' cables to each other thus making a connection like: 25F > 25F<>25M > 25M 1 25 25 1 2 24 24 2 3 23 23 3 ... ... ... ... 23 3 3 23 24 2 2 24 25 1 1 25 you would have actually created an extension cable. I hope this information serves to help some others that were in search of answers about computer cables. If you do find any errors in the above text please let me know. Darrell Bivens Silver Bullet BBS (615) 337-9683 Compiled 12/6/93 *the end*