General Computer Science II - 64-bit processor

The 64-bit architecture is a new technology and therefore there is only limited number of software that is designed specifically for 64-bit technology available at this moment. Most of the software released so far seems to be concentrating on the 64-bit application for Servers – for e.g.: Solaris 2.5 which provides support for increased precision with 64-bit math and for 64-bit asynchronous I/O and Solaris 2.6 Operating Environment which added support for large datasets with large (1 Terabyte) filesystem while allowing the coexistence of 32-bit and 62 bit files. Sun introduced, beginning with Solaris 7 Operating environment the support for large virtual address spaces with a full 64-bit operating system. (Reference: http://wwws.sun.com/software/solaris/faqs/64bit.html). SuSE Linux has also announced the shipment of the SuSE Linux Server 7 for the 64-bit IBM eServer Series on April 30, 2002.

Similarly, another major Linux Vendor – RedHat Inc. has also released Red HatLinus 7.1 for pSeries which is meant to allow the users to run data intensive workstation applications cost effectively and also create scalable clusters for high performance computing parallel computing. (Source: http://www.redhat.com/software/eserver/pseries)

Microsoft Corporation has brought out its Windows Advanced Server which it claims that it breaks the 4 GB / 64 GB memory limited and extends the operating system to 64 GB of Memory and beyond. Microsoft claims that the technology is backwards compatible, i.e. the application made for the 32 bit computers will still run unmodified even on the 64 bit architecture.

Compared to the software available for the 64-bit servers, currently there is only a handful of software available for the PCs available. Microsoft has just released its Microsoft^® Windows^® XP 64-bit Edition Version 2003 on March 2003 (Source: http://www.microsoft.com/presspass/press/2003/mar03/03-28WinXP64BitPR.asp) According to Microsoft the client version is targeted at the business customers solving complex scientific problems, running high performance design and engineering applications or creating 3D animations the specific uses of Windows 64-bit edition include Mechanical Design and Analysis (e.g. Mechanical CAD, Computer Aided Engineering, Modeling…etc) , Digital Content Creation (e.g 3D Animation and Rendering), Digital Video Editing, Visual Effects … etc) , Scientific/High Performance Computing (Simulations, Analysis…etc) and Financial (Data Analysis and Visualization). (http://www.microsoft.com/windowsserver/64bit/aslefaq.mspx).

In 14^th February, 2000, ATI technologies Inc. which is the world’s largest supplier of 3D graphics and Multimedia technology announced that it will be ready with a version of software drivers optimized for Intel Itanium™ processor. It has claimed that ATI’s Windows 2000 graphics software will be IA-64 compliant. It has also committed its support for IA-64 based applications on several non-Windows operating systems. (Source: http://www.ati.com/companyinfo/press/2000/4276.html)

At the moment, the most popular programming ANSI C, K&R C, ANSI C++. FORTRAN 77 and FORTRAN 90 support the emerging 64-bit technology. 64-bit Java Technology implemented by IBM has been used by Micromass, a lifescience company that developed tools for searching the Human Genome Database quickly via the web. (Source: http://www-3.ibm.com/solutions/lifesciences/news/java.html) Similarly, The AMD announced in January 22, 2003 that it was working with the Numerical Algorithms Group to develop the AMD Core Math Library (ACML) for AMD’s upcoming AMD Opteron™ and AMD Athlon™ 64 processors. According to the release, it is asserted that the library will be made available with both FORTRAN and C interfaces and will comprise of full implementation of Basic Linear Algebra Subroutines, Linear Algebra Package and Fast Fourier Transforms in single, double, single-complex and double-complex data types. (Source:http://www.amd.com/us-en/Corporate /VirtualPressRoom/0,,51_104_543_544~65950,00.html

As we have seen that the major application of 64-bit technology lie in the areas where there are huge computation and necessity of huge file retrieval. Why is 64-bit technology required instead of 32-bit technology? The answer lies in the fact that with 64-bit technology, the 4GB/64GB memory limit is broken. In Windows Advanced Server, for example, the 64-bit OS supports 64 GB of memory and beyond. In addition the applications can address 16 terabytes of virtual memory. (Source: http://www.microsoft.com/windowsserver2003/64bit/aslefaq.mspx ). Another notable feature of the 64-bit architecture is that it uses pipelining method which reduces the processing time as more than one process is underway at the same time. In the IA-64 architecture, there occurs a parallel execution of up to 6 instruction and uses a “pipeline” of 10 stages. (Source: http://www.hardwaresite.net/ia64.html) Speed of processing and transfer speed is crucial in places dealing with large amount of data transfer and processing such as those in Simulations and modeling. Quicker processing speed implies that the calculations can be made quicker and this in turn means more instances of simulations can be covered in a given time period than when the same thing was processed with a slower processing speed. Because of the promise of speed, the 64-bit technology has become so important in the field of complex computations.

As usual, when a new technology evolves, it is important that the technology is backwards compatible. In case of the IA-64, the compatibility of the 32-bit software in 64-bit environment has been assured by many organizations involved in this field such as Microsoft (Source http://www.Microsoft.com/windowsserver2003/64bit/aslefaq.mspx). It asserts that the application software running on the 32-bit system can still run in the 64-bit system. Similarly, Sun Microsystems Inc. assures that 32 bit application will run without modification in the Solaris Operating environment and that the 32-bit application run at full hardware speed on 64 bit UltraSPARC^® processors.(Source: http://wwws.sun.com/software/solaris/faqs/64bit.html). Microsoft already recommends running 32-bit software on 32-bit environment which implies that 32-bit software run slower on the 64-bit machines. This is of course the claim of the respective manufacturers and it obviously takes time to see if their claim is correct.

Another important question that arises is how the programming needs to be changed to suit the new system. As already discussed, the software complied under 32-bit environment can still run in the 64-bit environment. However, if the software is to be recompiled in a 64-bit environment, it needs some change. There are mainly two issues involved. The first one is that if there will be interoperation between applications using different data models. Since both 32-bit environment and 64-bit environment software run in 64-bit environment, there should be a proper mechanism for interoperation. At best, the 32-bit software can be recompiled for use in 64-bit environment and relinked with 64-bit libraries but sometimes it is necessary to change the data model. The 32-bit C data-type model is called ILP32 model in which the integers, long numbers and the pointers are 32 bits long. The 64-bit data-type model is called LP64 model in which the integer remain 32 bits long while the long numbers and the pointer grow to 64 bits. In the 64-bit model as well the standard relationship of C-integral types is still true:

Serial No	C Data Type	32-bit architecture	64-bit architecture
	`char`	8	unchanged
	`short`	16	unchanged
	`Int`	32	unchanged
	`long`	32	64
	`long long`	64	unchanged
	`pointer`	`32`	64
	`enum`	32	unchanged
	`float`	32	unchanged
	`double`	64	unchanged
	`long double`	128	unchanged

Therefore, at the beginning of this technology, it is inevitable that this could make the software development tedious as the existing software need to be recompiled or even modified to suit the needs. Moreover, it is also the programmers who need to get used to the 64-bit development environment. However, when this technology takes its market and when there are more software made exclusively for the 64-bit technology, the problem should be solved then. It is always the matter of time and hopefully soon, the problem of compatibility will be resolved.