If you take a look to the wire port of your HP48 you must note that it has a particular size, the pins are too close (2 mm to be exact), that is the main problem on getting a connector wich fits on the calculator and that is the main trick from our "friends of HP" to make us buy their "special" serial cable. It seems to be unique.
Well, actually it is not unique; In my particular case, I went to the downtown of my city (Mexico City) and looked for this kind of plug, I was lucky and got a connector from an old VCR wich fits perfectly on the port of my HP48, it is a little red plug, it use to be connected on the main board of the VCR; I am sure if you try to find a cable wich such especifications on Radio Shack you will never find it but come on, you can search on the large deposits of old electronic machines and you'll find a connector with the required especification and surely for a minimum price. Just remember to look for a cable with 2 milimeters of separation between pines.
Maybe you have found a cable for this purpose or you know where to find it at your particular city, if you did please send me a mail and I'll post it.
Remember, if you have any question or suggestion send me a mail
I will answer you as soon as posible.
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