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7-Zip vs. Win9x - .7z archive compatibilty

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First post, by soggi

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Hello everybody!

My first Thread here on VOGONS ... yeah! 😀

As some (or even some more) of you may know, I have a website (soggi.org, yes I'm working on the next update for over four years now 😒) where I provide in particular downloads like BIOSes, drivers, manuals, tools/utilities, (3dfx) game patches, video card tech demos or firmware for older motherboards, video cards and stuff together with some information (motherboard specification pages f.e.). These downloads are available as .7z archives for some years, because .7z/LZMA2 (Ultra) has a very good compression rate and 7-Zip by Igor Pavlov is tiny (non-bloated) open source software (OSS) which I recommend to use for archiving for many years.

Since my website is intended to work flawlessly on very old/slow systems and browsers, it was created using HTML 4.01 Strict w/o any JavaScript (except for Matomo [formerly Piwik], not necessary to function) - it has been successfully tested with graphical DOS Browser, for instance - and it is reachable via both HTTP/HTTPS. Therefor it is intended to have .7z archives as downloads which are most compatible and can be opened with the latest official (non-beta) version of 7-Zip for Win9x (version 9.20).

The archives are created on my daily driver, a WinXP SP3 POSReady "hacked" system and because 7-Zip still supports it, I have the latest version of it installed (at the moment it's version 24.08). With version 24.05 the following has been introduced:

https://www.7-zip.org/history.txt wrote:
- New switch -myv={MMNN} to set decoder compatibility version for 7z archive creating. {MMNN} is 4-digit number that represents […]
Show full quote

- New switch -myv={MMNN} to set decoder compatibility version for 7z archive creating.
{MMNN} is 4-digit number that represents the version of 7-Zip without a dot.
If -myv={MMNN} switch is specified, 7-Zip will only use compression methods that can
be decoded by the specified version {MMNN} of 7-Zip and newer versions.
If -myv={MMNN} switch is not specified, -myv=2300 is used, and 7-Zip will only
use compression methods that can be decoded by 7-Zip 23.00 and newer versions.

So I have to create the archives using the switch -myv=0920, I guess!? I always mark the files followed by right click -> 7-Zip -> Add to archive... and then there's a field for parameters. I tried both parameters (-myv=0920 and -myv=2300) and w/o and all three archives have the same MD5 sum (5f1a2ab5a2ff6506319dbff0e399007d). So this doesn't help.

Did I something wrong with the parameter? I want to know what's the latest possibility/version to create LZMA2 compressed .7z archives which are compatible with 7-Zip 9.20. As I don't have a working Win9x system, I can't test the archives myself with 7-Zip 9.20 in such an environment. Can someone test these please? Despite I guess all three are the same, I'll upload all...

The sample .7z archives contain No One Lives Forever (NOLF) MapPack 1, there's no special meaning about choosing this.

kind regards
soggi

Attachments

  • Filename
    NOLF_MapPack-1_noparam.7z
    File size
    2.28 MiB
    Downloads
    21 downloads
    File license
    Fair use/fair dealing exception
  • Filename
    NOLF_MapPack-1_0920param.7z
    File size
    2.28 MiB
    Downloads
    12 downloads
    File license
    Fair use/fair dealing exception
  • Filename
    NOLF_MapPack-1_2300param.7z
    File size
    2.28 MiB
    Downloads
    23 downloads
    File license
    Fair use/fair dealing exception
  • 7-Zip_param.png
    Filename
    7-Zip_param.png
    File size
    26.33 KiB
    Views
    697 views
    File license
    Fair use/fair dealing exception

Vintage BIOSes, firmware, drivers, tools, manuals and (3dfx) game patches -> soggi's BIOS & Firmware Page

soggi.org on Twitter - inactive at the moment

Reply 1 of 12, by Stretch

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I was able to extract all 3 archives with 7-Zip 9.20 in Windows 95. The test archive function in the right-click menu also passed on all 3 archives.

Win 11 - Intel i7-1360p - 32 GB - Intel Iris Xe - Cubilux 7.1 USB

Reply 3 of 12, by 1541

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Why not ship the them as self-extracting (.EXE) files? (Like WinZip did it back in the days)

That way 7z does not need to be installed on Win9x at all.

💾 Windows 9x resources (drivers, tools, NUSB,...) 💾

Reply 4 of 12, by soggi

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Stretch wrote on 2024-10-14, 20:53:

I was able to extract all 3 archives with 7-Zip 9.20 in Windows 95. The test archive function in the right-click menu also passed on all 3 archives.

Thanks for testing! 😀

This is weird, why they write then that I need a parameter to create compatible archives!? As said, I guess all three archives are the same (same MD5) so the parameter didn't work at all...

So I can repack all files with the latest version of 7-Zip (24.08 at the moment).

DosFreak wrote on 2024-10-14, 20:58:

Why is 9x necessary to test? Just use the old very on a new os

Indeed, that's right. I wanted to be 100% sure that it works on Win9x, that's the simple reason. Occasionally I have visitors with Win9x or WinNT4 and I want them to be successful and confident while using my website. 😀

1541 wrote on 2024-10-14, 21:13:

Why not ship the them as self-extracting (.EXE) files? (Like WinZip did it back in the days)

That way 7z does not need to be installed on Win9x at all.

Indeed, that's right too. I had some thoughts on it but it never felt right to have .exe files as downloads. They can be suspicious to someone and there may be "security software" which prevents .exe files from being downloaded, so it's more compatible to have .7z files.

kind regards
soggi

Last edited by soggi on 2024-10-15, 16:51. Edited 1 time in total.

Vintage BIOSes, firmware, drivers, tools, manuals and (3dfx) game patches -> soggi's BIOS & Firmware Page

soggi.org on Twitter - inactive at the moment

Reply 5 of 12, by maxtherabbit

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I'm not aware of any changes in the 7z format which broke backwards compatibility. I have yet to encounter a 7z file which would not extract on my win98se machine.

Reply 6 of 12, by chinny22

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soggi wrote on 2024-10-14, 21:56:
1541 wrote on 2024-10-14, 21:13:

Why not ship the them as self-extracting (.EXE) files? (Like WinZip did it back in the days)

That way 7z does not need to be installed on Win9x at all.

Indeed, that's right too. I had some thoughts on it but it never felt right to have .exe files as downloads. They can be suspicious to someone and there may be "security software" which prevents .exe files from being downloaded, so it's more compatible to have .7z files.

I agree with this, Typically I'll right click and extract just to be on the safe side.

Reply 7 of 12, by soggi

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maxtherabbit wrote on 2024-10-14, 22:56:

I'm not aware of any changes in the 7z format which broke backwards compatibility. I have yet to encounter a 7z file which would not extract on my win98se machine.

But the changelog exactly says this...as quoted above. Confusing.

chinny22 wrote on 2024-10-14, 23:31:
soggi wrote on 2024-10-14, 21:56:
1541 wrote on 2024-10-14, 21:13:

Why not ship the them as self-extracting (.EXE) files? (Like WinZip did it back in the days)

That way 7z does not need to be installed on Win9x at all.

Indeed, that's right too. I had some thoughts on it but it never felt right to have .exe files as downloads. They can be suspicious to someone and there may be "security software" which prevents .exe files from being downloaded, so it's more compatible to have .7z files.

I agree with this, Typically I'll right click and extract just to be on the safe side.

Thx for the confirmation, I also extract SFX files always this way - to be on the safe side and because it's much faster (I always chose "Extract to directory with file's name").

Edit:
BTW I found this discussion about the new switch on SourceForge -> https://sourceforge.net/p/sevenzip/discussion … ead/7e8a02dac8/.

kind regards
soggi

Vintage BIOSes, firmware, drivers, tools, manuals and (3dfx) game patches -> soggi's BIOS & Firmware Page

soggi.org on Twitter - inactive at the moment

Reply 8 of 12, by bakemono

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maxtherabbit wrote on 2024-10-14, 22:56:

I'm not aware of any changes in the 7z format which broke backwards compatibility. I have yet to encounter a 7z file which would not extract on my win98se machine.

A build of 7ZA (command line util) from 2006 barfs on a lot of 7z files these days, saying "unsupported method", so there must have been changes since then at least.

GBAJAM 2024 submission on itch: https://90soft90.itch.io/wreckage

Reply 9 of 12, by Norton Commander

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soggi wrote on 2024-10-14, 18:03:

Since my website is intended to work flawlessly on very old/slow systems and browsers, it was created using HTML 4.01 Strict w/o any JavaScript (except for Matomo [formerly Piwik], not necessary to function) - it has been successfully tested with graphical DOS Browser, for instance - and it is reachable via both HTTP/HTTPS. Therefor it is intended to have .7z archives as downloads which are most compatible and can be opened with the latest official (non-beta) version of 7-Zip for Win9x (version 9.20).

Thanks for this - I didn't know there was a version of 7-Zip that was compatible with Win9x. Everytime I downloaded a .7z file I had to first convert it to .ZIP on my Windows 10 machine then transfer to Win9x.

Reply 10 of 12, by DosFreak

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DOS
v16.02
7-Zip Benchmark, DOS Edition

3.51-NT4
9.20

95 (not sure which ver I tested but its usually the first one, GUI worked fine for me at the time)
9.30

98-ME
9.30

98-ME (KernelEX)
7z1900 (Haven't tested since)

2000
7z2404 (Haven't tested since)

How To Ask Questions The Smart Way
Make your games work offline

Reply 11 of 12, by soggi

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Norton Commander wrote on 2024-10-15, 17:09:

Thanks for this - I didn't know there was a version of 7-Zip that was compatible with Win9x. Everytime I downloaded a .7z file I had to first convert it to .ZIP on my Windows 10 machine then transfer to Win9x.

You're welcome! 😀

I have some more tools etc. and their latest versions for several OSes collected on my tools/utilities page -> https://soggi.org/misc/tools.htm. Just in case, maybe you find some other useful tool.

---------------

@DosFreak:

Yes, I remember someone compiled 7-Zip 16.02 for Win9x (and obviously even for DOS).

Windows 2000 doesn't need a special version, the latest official version should work flawlessly.

kind regards
soggi

Vintage BIOSes, firmware, drivers, tools, manuals and (3dfx) game patches -> soggi's BIOS & Firmware Page

soggi.org on Twitter - inactive at the moment

Reply 12 of 12, by maxtherabbit

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bakemono wrote on 2024-10-15, 16:28:
maxtherabbit wrote on 2024-10-14, 22:56:

I'm not aware of any changes in the 7z format which broke backwards compatibility. I have yet to encounter a 7z file which would not extract on my win98se machine.

A build of 7ZA (command line util) from 2006 barfs on a lot of 7z files these days, saying "unsupported method", so there must have been changes since then at least.

Ok but those same files extract on gui version 9.20?

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