On 7/10/2011 10:25 AM, Bernd Blaauw wrote:
> Mike,
>
> do you have any experience using UPX (executable file compressor) on
> your programs? I'm wondering if
> 1) programs still load properly for you on 8086
> 2) smaller disksize + in-memory-decryption faster than loading entire file.
>
> I'm pretty sure the compression program itself is 386+ or 586+,
> but compressed executables should be 8086+ if used with proper options.
> (upx.sf.net ) , upx --best --8086 c:\mtcp\*.exe
>
>
>                          Ultimate Packer for eXecutables
>                             Copyright (C) 1996 - 2010
> UPX 3.07d       Markus Oberhumer, Laszlo Molnar&  John Reiser
>
>           File size         Ratio      Format      Name
>      --------------------   ------   -----------   -----------
>        51974 ->      32191   61.94%     dos/exe     dhcp.exe
>        39372 ->      25975   65.97%     dos/exe     dnstest.exe
>       102256 ->      56758   55.51%     dos/exe     ftp.exe
>       111996 ->      58321   52.07%     dos/exe     ftpsrv.exe
>        87044 ->      48833   56.10%     dos/exe     ircjr.exe
>        76430 ->      44563   58.31%     dos/exe     nc.exe
>        40092 ->      26488   66.07%     dos/exe     ping.exe
>        41660 ->      27319   65.58%     dos/exe     sntp.exe
>        69230 ->      40488   58.48%     dos/exe     spdtest.exe
>        86730 ->      48854   56.33%     dos/exe     telnet.exe
>      --------------------   ------   -----------   -----------

I tested UPX on one of the slowest machines that I have that has a hard 
drive.  On a PCjr with a NEC V20 and XT-IDE adapter UPX compressed 
executables worked, but they took noticeably longer to start up:

     FTPSRV: original was 2 seconds, with UPX is 5 seconds
     PING: original was 1 second, with UPX is 2 seconds

The V20 makes the machine a little faster than a standard 8088 based 
machine.  The XT-IDE adapter is slow as far as hard drive controllers 
go; on a real XT the delay would be more pronounced because the 
controller is far better.  But on an 80286 or better I'm sure that the 
difference is not noticeable.

I think that most people are running on faster hardware with plenty of 
storage space, so this is interesting but probably not worth making part 
of the build process.  (Is my instinct correct here?  I think I'm one of 
the few nut jobs on 8088 based hardware, because it's fun!)

On a slightly off topic note, I need to learn to build FreeDOS.  I 
suspect it doesn't like my PCjr and I'm going to have to fix that. :-)


Mike


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