>> It could also depend on the fact that 4 and 16 are exponents of 2, but 20
>> and 24 are. Could you possible try 32?
>> 
>The problem is something with the LANCE addressing of memory. The LANCE
>chip can only address 16MB of memory, and by some unknown reason it works
>good when there are less than 16MB in the machine.

For the VS3100, ULTRIX and VMS always allocated some extra RAM (below 16M)
to copy the data if wasn't < 16MB.  

For later VAXstation (VS4000VLC or /60 or /90), a scatter-gather map was 
included (or the design used the SGEC chip).
-- 
Matt Thomas               Internet:   matt@3am-software.com
3am Software Foundry      WWW URL:    http://www.3am-software.com/bio/matt.html
Nashua, NH                Disclaimer: I disavow all knowledge of this message