During the development of PKZIP v. 2.0 for MS-DOS, PKWARE has 
discovered hardware faults in newer 80386 & 80486 computers. 
These faults can cause anomalies in the operation of PKWARE 
software as well as other software.

PKWARE has been endeavoring to locate an anomaly that has been 
observed by a number of customers and associated vendors.  The 
intial symptoms of the problem were:
        
  - Particular files extracting with errors on one machine, but not
    on another.  
       
  - Installs of some products failing.

These problems have been observed primarily on newer, fast (33Mhz 
or faster) 80386 and 80486 machines.  Investigation of the problem 
revealed no difference in software or hardware between machines 
that failed and machines which did not.  The files which fail do 
not fail every time.

To further test where the problem was occuring, a very simple 
program which would load a test file into a RAM buffer and then 
copy it to a second RAM buffer was created.  The program then 
compares the two buffers one byte at a time and reports any 
discrepancies.  Discrepancies with even the simple copy were 
noted.

If the EXTERNAL CACHE is turned off through the BIOS 
configuration, the problem does not occur.

This is indeed a hardware flaw. 

While this effort to work around these hardware faults will, 
unfortunately, delay the release of PKZIP v. 2.0 for MS-DOS, we 
hope to release it in the next few months.
 
We know you will be pleased with the many new features and 
enhancements to PKZIP.  We appreciate your understanding and 
patience in our efforts to provide reliable software.

Sincerely,

PKWARE, Inc.