32 bit applications in general

[ASOEASTGEOGRAPHY]

1- Can a 32 bit app talk to a 64 bit APP? If yes, what are the limitations?

2- Do all 32 bit apps are limited to the same space in terms of virtual memory?

[Paula J Frazer-Campbell]

Hi

32 bit apps will talk to a 64 bit app directly providing that the 64 bit app will accept data in 32 bit chunks, the limitations mainly are that the 64 bit applications will be slower.


Paula

[Bill Hassell]

32 bit and 64 bit apps can communicate through standard methods (shared memory, message queues, memory mapped files, ect). But a 32 bit app cannot access any data elements beyond 32 bit limitations. For instance, shared memory in 64 bit can be up to 8,000 Gbytes in size.

Also, the default data model is slightly incompatible for long and pointer (32 vs. 64 bits). Now if the defining application is 32 bits, then a 64 bit program would have access to the data but unless explicitly overridden, longs and pointers would mismatch. Thus, the programmer must explicitly code for 32 bit comptibility.

As far as speed differences, that is very difficult to compare. Significant rewrites of some libraries for 64 bit implementations are significantly faster, so the code will run much faster with certain calls. But in general, the difference isn't a lot. 64 bits virtually eliminates addressing limitations (for now). Be sure to look at the Software Transition Kit at:

http://www.software.hp.com/STK/