Get your own Free Home PageSeveral PC programs, X1541, Trans64, ... use a cable from a PC printer port to emulate a Commodore computer serial bus port to operate a Commodore disk drive. Other PC s/w can act as a disk for a C= computer. This is an easy way to get a Commodore file from the internet, through a PC, into a Commodore computer. Just write it on a 1541 floppy disk and put the floppy into a drive on your Commodore.
To try it out, I downloaded NovaTerm 9.5 to a PC, wrote the files to C= floppies, ran the self-dissolving archives on a C= SX-64, and ran the resulting NovaTerm program on the SX-64. It all worked nicely, but I could have saved some time by reading directions. It also worked on a 1571.
The design of the cable must match whatever PC program is going to be used, the X1541 cable is most common. I decided not to cut the end off of a C= drive serial bus cable, but to simplify building the cable, I used a very common PC printer cable. I chose a cable which had a removable hood on the 25 pin D connector (PC end), but it is not necessary to remove the hood, a fully molded connector would be ok. I cut the cable in the middle to make a 3 foot cable to the 1541. The only other part needed is a 6 pin DIN plug to put on the end of the cable, like the end of a C= serial bus drive or printer cable. I built a second cable with fully molded plugs which had different color codes. I made it five feet long and it also worked ok.
The whole job only needed seven soldered connections.
The wire colors below are the ones in the PC printer cable I used. Check your cable with an ohmmeter, or continuity tester; or open up the plug.
>>>First Cable; removable Shell<<<
PC Wire C=
LPT Color Bus Function: PC/C=
--- ------ --- --------------------
18-25.Blu/Wh....2...Ground/GROUND
1....Blk.......3...Strobe/ATN
14....Brn/Wh....4...AutoFeed/CLOCK
17....Grn/Wh....5...SelectIn/DATA
16....Orn/Wh....6...Init/RESET
Shell.Bare...Shell..Cable Shield
2....Brn.......-...db0 - To pin 15 wire, lets PC test the cable.
15....Red/Wh....-...error - To pin 2 wire, lets PC test the cable.
-....-.........1...Not Used
>>>Second Cable; Molded ("Made in China")<<<
PC Wire C=
LPT Color Bus Function: PC/C=
--- ------ --- --------------------
18-25.AQUA......2...Ground/GROUND
1....Brn.......3...Strobe/ATN
14....Wh........4...AutoFeed/CLOCK
17....PINK......5...SelectIn/DATA
16....Blk/Wh....6...Init/RESET
Shell.Bare...Shell..Cable Shield
2....Brn/Wh....-...db0 - To pin 15 wire, lets PC test the cable.
15....BLK.......-...error - To pin 2 wire, lets PC test the cable.
................1...Not Used
The two wires from pins 2 and 15 of the printer port are soldered together and insulated, in the back of the DIN plug; they do not connect to the C= plug pins.
Shielded cable is best. The shield had a bare wire soldered to the metal shell of the PC end and I soldered the bare wire to the metal shell of the C= DIN plug. Connecting the shield at only one end would be ok if it has an all plastic plug.
The printer cable had ground pins 18-25 all bussed together inside the DB-25p connector that plugs into the PC printer port. This was very handy. A general purpose RS-232 cable with a Male 25 pin connector would not have the convenient grounding, and might not have the other pins wired the way we want them.
Most, or all, 25 pin D connectors have pin numbers marked on the insulator of the plug. If you hold the male plug with the pins facing you and the longer row on top, then Pin 1 is on the top-left. From behind, where you connect the wires, pin 1 is on the top-right.
Some C= DIN plugs have no pin numbers at all. When you hold the male pin plug with the notch and gap at the top and the pins facing away, pin one is at the upper-right and the pins count-up clockwise (and #6 is in the middle). The same pattern is seen on the face of a female DIN socket.
There are many ASCII-Art attempts to draw the connectors.
DB-25 PC printer port. Commodore 6 Pin DIN
-----\ v notch
| 1 \____
| 14 | 5 * 6 * 1
| 2 | *
| 15 | 4 * * 2
| 3 | *
| 16 | 3
| 4 |
| 17 | Back of male pins.
| 5 | Face of female socket.
| 18 |
| 6 | One design listed these colors for
| 19 | a Commodore Serial bus cable:
| 7 | 1 - not used
| 20 | 2 - Black
| 8 | 3 - Red
| 21 | 4 - Blue
| 9 | 5 - Yellow
| 22 | 6 - Green
|10 | {I have not checked them}
| 23 |
|11 |
| 24 |
|12 |
| 25 |
|13 /---- Back of Male pins or
-----/ Face of Female socket
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