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Comment by whizzter | Hacker News Reader

Iirc you could split files with Zip at that time as well, but the major annoyance was that you always needed to insert the last disk of the Zip set at the start. This made it so that compressing and copying between 2 computers by moving one or two disks between the computers was impossible, requiring a full set of disks.

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pkzip also wouldn't create the split archives on your hard drive. It had to actually write to the disks and experience the disk full error for itself. No fun, because you'd have to babysit the whole process, which would take longer than normal due to the compression, without knowing how many disks you'd need. You also had to just hope that none of them would turn out to have errors.

With arj you could tell it you wanted each part to be whatever size would fit on a 1.44 MB DOS disk, leave it going, then do the copy-to-disk step afterwards having been forewarned about how many disks you'd need.

You could also do this with RAR. I always used the same command (which I could still recite up to the last character) to create compressed files of the size of a floppy, which I believed to be exactly 1423.5 kilobytes. Then again, I'm not sure where did this number come from. I think I used the first disk I could find as a sample, but maybe that disk had some faulty sectors and the amount in a healthy disk was slightly higher.

I remember, back in the day, trying all the compressors I had at hand to see which one compressed the most. Possibly one of my first truly self-researched bit of computer knowledge... not very impressive, but then again this was the mid-90s and I was like 13. I believe that the answer was something like RAR > WinRAR > ARJ > PKZip > WinZip, with the difference between RAR and WinRAR, and between PKZip and WinZip, being very small, and the other two gaps being higher. I probably botched some settings regarding compression levels, so it's likely that I didn't use the best compression level for some of the compressors.

> Iirc you could split files with Zip at that time as well, but the major annoyance was that you always needed to insert the last disk of the Zip set at the start.

I remember that! Was it some technical detail of the .zip format, or just poor design choice?

The "central directory" of a ZIP archive is at the end of the bitstream; so, yes, it's a consequence of the format.

Because of this, if I'm remembering correctly, you can append a .zip file to, say, a .jpg file and it will work most image viewers and as a zip archive. It used to be the case, anyway, I haven't tried it lately.

This is how some self-extracting .exe files work, too. You modify the unzip command to use its own filename instead of an argument, and then you append a zip to the end of that.

I (and others in demoscene and gamedev) often used this "trick" to avoid having extra resource-files and just distribute a single .exe (that was in reality a small exe plus a huge zip appended just behind it).

Works well because Windows just reads the MZ and then PE headers that says where the EXE data is (up to the original .exe size). Then the .ZIP central directory pointer is easily findable at the end of the file so it works fine after appending.

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