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I know this probably has been covered somewhere before, but what computer connector can one use to plug into the 4 pin of the hp 48?

Is it the 4 pin floppy power connector with the edge trimmed?


It is the 4 pin connector from a CD drive audio output. 2mm pin spacing.

hmm, doesn't seem to work for me. Have you tried it personally yourself?


the 4 pin plug seen in the above cable doesn't look like that from audio cable. But i don't know where or what part it's from.

I hate to get the real cable. They are a rip off. Esp from people on ebay.

I got a serial connector from radioshack for $2. Now if i can find the 4 pin plug.

Unfortunately the above site doesn't sell anymore. otherwise i would have bought it. $7 is a good price. no more.

IIRC my first serial connector was called SPB4,

a flat anthrazite plug with one side diagonally cut.

It didn't really hold in place very good, but it had the right 'pinhole' distance.

A floppy plug didn't work, because the footprint of the plug was too wide.

You would have to cut two of the edges for the plug to fit into the HP-48's connector hole.

If you're really interested, I can check if I still have one of those SPB4,
and send a photo;-)


Sure ;)

I tried to trim the sides of the floppy connector, but i am really wondering if the pinhole distance is of the right amount.

Here's a photo of four plugs:

- Original HP plug for HP-48

- Rebuilt W&W plug for HP-48

- Floppy disk drive power connector

- Siemens SPB4 mini plug

Forget the floppy connector, it's the worst of the 4 options.

The pin hole distance is somewhat too far, and it's a very unergonomic plug.

I used the SPB4 at a time when the original HP cable cost about 50 Euros (converted from 100 DM),

but nowadays I wouldn't waste any time and money for such a bad solution like a floppy plug.

I'd suggest getting an original HP cable, or the generic one which some other vendor

(like Yellow Computing) used for their HP-48 connectivity kit,

with the correct and optimal plug on the HP-48 end, no hassle,

it just fits and works, and usually is available for a few bucks today.



Edited: 5 Feb 2008, 11:02 a.m. after one or more responses were posted

There is another option: The HP95LX has the same plug! If you find the connectivity kit for it, you get the right cable. I even have an adapter which maps the HP200LX plug (10 pin) to four pins.

Are the cables really the same? Or are there any differences in pinout? I'm not sure.

Hi Wildpig (hope that's not your real name - what is??)

Check out the following HP-48 Faq from the HPCALC site:

12.1 How to Make a Serial Cable

As Randy said, it's the CDROM audio cable - the smaller of the two connectors.

I just grabbed one here at work, and the smaller end does fit my HP-95LX which is the same connector as the HP-48.

Bill (my real name)
Smithville, NJ


I did mine with an old 2-buttons mouse cable. The size and the spacing of the pins (mouse side) are the same as those of my 48.

Hope it helps.

Kind regards.


about the HP cables and pinouts, there are some variants,

maybe Joe Horn's cable table has more details on this.

BTW I have a single cable with special, but original HP adapter plugs,

which fits all the HP-48, HP-38G, 49g, 95LX, and 200LX :-)

The central adapter for this is also in Joe's table (the rare bird)

Here are some pics:

The rare bird is the F1212-80001 Dual adapter, which AFAIK was only available with the overhead display kit,

the small ten-female-to-4-male plug is the 5181-6643 known from the newer connkit,

and the cable is the F1015-80002, also from the connkit.

Note the notch on the F1015-80002, and the notchless F1212-80001 .


BTW: As Alex also noted, we already burnt that much time on this topic, worth more than one original HP cable;-)

Edited: 5 Feb 2008, 12:50 p.m.


As Randy said, it's the CDROM audio cable - the smaller of the two connectors.

The cd audio connector both ends are the same and they don't fit my 48g. Am i doing something wrong? ;( Any other suggestion for a plug? thanks

There's more than one possible plug standard for the audio connector of a CDROM.

When it was interesting for me back in 1990, the older, bulkier plug with retention clip was widespread.

However, I still suggest getting the original cable, for the reasons mentioned in my other post.

There are zillions of original or compatible cables floating around for small money, so what ?

There are several configurations for the CDROM sound card cable. The most standard used one today is the MPC II connector on both ends. They are usually black.

There's also CDROM audio cables that go directly to other sound cards. These have the MPC II connector on one end to plug into the CDROM drive and a smaller white connector on the other end which will plug into the sound card. This is the connector you want. In some cases, the cable has both connectors on one end so that it can connect to either.

The following are links to some places where you could order the cable with the smaller connector:

Belkin Cable



Cable Warehouse

With the exception of PCConnection, I have not ordered from any of these places.

If you don't want to order one, then I'd suggest you just visit your local PC Computer repair shop, take your 48 with you and ask them if they have a CDROM audio cable laying around that would fit. Your best bet is a local, small computer dealer, etc. Although these are getting fewer and fewer. We still have several small home-type computer shops around in my area. But they are quickly fading from the scene.

Smithville, NJ

Edited: 5 Feb 2008, 10:52 a.m.

I hate to get the real cable. They are a rip off. Esp from people on ebay.

On ebay, I paid $10 + actual s/h, and I got the full kit (pc cable, calc-calc cable, 4/10pin converters, software). My time just to source the parts, let alone assemble them, is worth more than that. YMMV.

I tried radioshack where i got the serial connector. they gave me a funny look when i ask them about a 4 pin connector.

Yep, the day of being able to find parts for makeshift cable is quickly coming to an end. ;(

I gave up making my own cable ;(. saw a 10 pin inter calculator and serial cable with 10 to 4 pin adaptors for use with hp49 and hp48 on ebay for $17 so i bought that.

now i can also interface with hp49 if i ever get one or have a need to interface with one.

I made a cable once for my 48G and G+. I got the four-socket connector, for the four pins in the calculator's port, from either Samson Cables or Calcpro (I forget which now), back when they were still more readily available.

The problem was that my homemade cable, while it fit properly to both the calculator port and the computer port, it was rather clumsy on the calculator side; the connector was difficult to put into the port, kinked a little where the wires were soldered onto the connector, and sometimes fell off unexpectedly.

Then I finally bought one (and I again forget which of the two sources I used) and am happier with it.

I made the cable originally because I used to make my own connectors from multiwire cables for all sorts of equipment. But for those, I had very well manufactured connectors that fit the equipment it was intended for quite well. The available four-hole connector then was too simply made and there was no provision for securing the connection once the connector was put on the pins.