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| LocalTalk cables: crossed-over wiring or straight-through? |
Posted by: bigmessowires on 2023-09-04 14:03:06
I know LocalTalk cables are Mini DIN 8, but I'm not sure about the wiring. For directly connecting two Macs, should the cable be wired straight-through, or crossed-over with the TXD and RXD pairs swapped? I'm thinking they should be swapped, in which case this cable will not work: https://files.cablewholesale.com/pdfspecs/10m3-041xx.pdf Could somebody confirm? |
Posted by: bigmessowires on 2023-09-04 14:04:42
...and if memory serves, serial cables use the same Mini DIN 8 connector, but are not crossed-over? |
Posted by: ClassicGuyPhilly on 2023-09-04 14:13:47
I used a standard printer cable to connect my PM7500 to my SE |
Posted by: cheesestraws on 2023-09-04 14:21:09
Standard Apple serial cables are always crossed over, regardless of whether they are mac-mac or mac-printer.
Some third-party ones are straight-wired, for some reason, and don't work properly with anything. I assume there is some peripheral out there that liked that, but I've no idea what it was.
And I've got a third-party one here that's cross-wired but only wired for RS232, and that one is baffling. |
Posted by: bigmessowires on 2023-09-04 14:22:42
I'm really confused by this product: https://www.cablewholesale.com/products/apple-products/legacy-apple-products/product-10m3-04106.php
It specifically says it's a serial cable for legacy Macintosh, but if the datasheet is correct it's wired straight-through. |
Posted by: mdeverhart on 2023-09-04 18:50:40
My recollection is that modems and things that follow the DCE/DTE relationship use straight-through cables, while printers and point-to-point LocalTalk use the crossover. |
Posted by: Forrest on 2023-09-04 21:33:16
bigmessowires,
The straight thru serial cable is likely meant to be used with a manual switch box such as https://www.cablesdirect.com/store/p/2250.aspx |
Posted by: gsteemso on 2023-09-09 13:52:23
bigmessowires,
The straight thru serial cable is likely meant to be used with a manual switch box such as https://www.cablesdirect.com/store/p/2250.aspx I had one of those "back in the day" and was initially baffled that it didn't seem to work. I eventually determined, with outraged disgust, that they had failed to cross over the wires internally to the switchbox, so I had to hand-build a straight-through cable before I could do anything with it.
So far as I'm aware, only one Apple product ever used a straight-through mini-8 serial cable, and the existence of the cable specific to that product caused extensive wailing and gnashing of teeth for many years in the 1980s. The wretched things were visually indistinguishable from all that came later, except for the tiny model number moulded into the bottom of the plug on the end, so if you were unlucky you'd occasionally get a serial cable that mysteriously just didn't work. (I _believe_, without having verified it physically, that the product in question was a very early Apple-branded printer. For a long time I'd been under the impression it was the original ImageWriter I, but ISTR later discovering that those didn't even have a mini-8 connector, so now I really have no idea.) |
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