Swap Disk Indexing Project

This is a call for data, and/or comment and/or participation in a project to produce an index for the varios LIF images collectively known as "the Swap Disks." I'm sure that this has been done, probably more than once over the years, but I don't see an extant index out on the Internet. What I plan to do is to put up a wiki (Twiki, probably) at retrocalculator.com where people can add entries against file names in the raw LIF directory listings. I will have to ask for registration, because of the problem of SPAM bombing and vandalism that wikis are subject to.

Some inital thoughts I have, open to discussion:

The index should be free, like in beer, as the swap disks themselves are.

Personally, I'd prefer if it were Free, like in freedom, as in the Gnu Free Documentation or one of several Creative Commons licenses. This is certainly open to discussion.

The index doesn't have to be comprehensive to be useful. Therefore, wiki content will be distilled into the canonical index on a frequent basis.

The wiki should be free-form, but the index should be rigidly structured. This matches the needs of humans on the one hand and computer searching on the other.

I propose not to provide a discussion forum, since there is already a very nice one here, and the subject is on-topic. This is, of course, subject to Dave's requirements.

I can host a mirror of the swap disk archive or use the (now canonical) copy here.

If there is interest, new swap disks could be produced. I see no archive of 71B software other than the swap disks, for instance. I'd be glad to host one.

(I think) I have every machine whose software appears on the swap disks except for the 75D. Those would be the 41C, 75C and 71B. I also have the capability to load LIF formatted data on to each of those. That means I can try figuring out what a particular file does for each of the three machines. I can also convert media from LIF to modern formats.

I'm willing to do much of the work. However, my day job is about to spin up again, so It will be a part-time effort after the initial push. Help would be very welcome, and ought to speed the process along. But I'm committed to following through on this regardless, since it falls squarely within my hobby interest: old calculator software and systems.

If you are interested, please drop me a line, or reply here. I need to gauge how much interest there is before I go through the not inconsiderable labor of setting up Twiki. If it's just me and one or two others, I won't bother with that part.




In the last several years I have become interested in collecting, using, and "playing with" HP calculators. I own HP41C, HP71B, and HP75D calculators, and quite a few peripherals, and original software and ROM pacs. I have several original "swap" disks from Educalc. I do not know how to extract the LIF file images on the MoHPC ftp site for my use, although I have tried using HP utility files. I am willing to help, and support your effort any way I can. I am retired and have plenty of free time. And maybe I'll learn something. Let me know what I can do to help.

Thanks for your interest in this project.

Best regards
John Pierce


Hi, John!

Yes, that's the tricky part - getting the bits on to the calculator/computer. I do it with an HP-IL ISA card built by Cristoph Klug. You should also be able to use an original HP HP-IL ISA card for this purpse. There's one being offered on eBay, the last I looked. You need a PC at least one ISA slot, which means an older one. But given that, you can then run J.F. Garnier's EMU41 in a DOS box (on Windows) or under DOSEmu (under Linux.) This gives you the capability to serve out LIF images to the loop, where you calculators and computers can get at the contents.

There are other ways to go. For the HP-41C, you can convert the raw bits (extracted with available tools for DOS or Linux) to barcode files, which you can then print and scan with the wand. This is tedious, so I never do it unless I have a 41C program in barcode only. The approach doesn't work for the 75C or 71B, but might for the 75D and wand.

What you can't do is write LIF images to floppy (that could then be read by a 9114) because the sector size of 256 bytes is unsupported in any PC BIOS past 1990 or so. I recently saw a dual SCSI 5 1/4" floppy set, and it occurred to me that it might be possible to read and write the lif disks directly using such a beast. However I don't have a 5 1/4" HP-IL floppy.


The LIF Utilities for Linux don't use the BIOS at all (they use the linux floppy driver which talks directly to the hardware). I have certainly read/written physical 3.5" disks in my PC and then stuck them in the 9114 with no problems.

Of course my PC is a lot older than 1990, but I don't think that's necesary for it to work.


Well, I can't get lifimage or lifdump to work for me on a ca. 1994 Compaq Pentium machine running Slackware 10. I have many newer machines that I haven't tried, tunning a variety of Red Hat flavors. I'll try some of them and report back.

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