Program Features/Hints

  •  You can abort compression and decompression at any time by pressing cmd-'.'.

  •  You can resize the progress window by dragging the lower right hand corner.

  •  MacCompress first utilizes available memory for compression tables, attempting to allocate enough to allow 16-bit compression and decompression.  After compression tables have been allocated,  I/O buffers are allocated.  Allocating more memory will result in fewer disk accesses, and hence faster operation.  Generally, if you are compressing large files, 600K or more of memory will result in CPU bound compression for maximum speed.  Allocating less than 512K with 16 bit compression under Multifinder results in a serious degradation of performance (more than a factor of 2).

  •  Under Multifinder, you can safely set MacCompress's memory allocation to as low as 150K.  Remember though, that for 16 bit compression and/or decompression, you need 480K or more -- smaller memory allocations prevent you from using more bits.   MacCompress dims appropriate items in the Bits dialog to indicate that it doesn't have enough memory for compression using that number of bits/code.

  •  MacCompress is Multifinder compatible, and will run quite happily in the background, (though more slowly of course, since it gets less of the CPU).  Since Mulfinder does not switch processes when there is pending I/O, compressing/decompressing lots of small files tends to result in rather sporadic response from foreground applications.  You should get reasonable response if MacCompress is running CPU bound.

  While in the foreground, there is a small time penalty for allowing background processes to run.  Therefore, if time is critical, run MacCompress using the Finder, not Multifinder.  If you do run it under Multifinder, closing all the Finder's windows and other applications will also speed things up. 

  •  Performance:  My brief tests using a RAM disk on a Mac II show that compression speed is roughly 27K bytes/sec and decompression speed is roughly 38K bytes per second for C source code.  The Mac II HD40 drops this to 18K bytes/sec and 21K bytes/sec, respectively.  Of course compressing many small files is slower still.  Your mileage will vary, depending on CPU, disk speed, and compression ratio.  (By comparison, Stuffit 1.31 compresses at roughly 13K bytes/sec and decompresses at roughly 17K bytes/sec on the Mac II HD40 on C source files).
  MacCompress also yields significantly better compression than Stuffit on some large files, but does about the same when many small files are compressed (due to the wasted space in disk blocks).