One of the big advantages of the EMME/2 system is the fact that the exactly same code runs on a variety of hardware platforms, such as PC/ATs in real mode addressing, 386/486 machines using protected mode addressing, PCs with 68020/68030 Definicon Coprocessor board, the various UNIX based mini-computers and workstations, the entire VAX/VMS line of computers, or even IBM mainframe machines. This makes it easy for users to carry out joint projects involving different EMME/2 installations or, if ever the need arises, to upgrade their system to a more powerful computer.
Up to now, the compatibility between different host machines was limited to the identical functionality and the exchangeability of the input files. This meant that it was not possible to use the EMME/2 data base files EMME2BANK on a system of different type than the one it was created on. Thus, switching from one type of computer to another one always implied that the data bases had to be rebuilt.
With the introduction of the new data base transformation utility E2XFBANK, this limitation has been lifted. It is now possible to transform existing EMME/2 data bases which were created on one type of host for use on another type of host. The following host systems are recognized by the E2XFBANK utility:
| I286 | Intel 80286 based PC/AT using real mode addressing |
| I386 | Intel 80386 or 80486 based PC using protected mode addressing |
| DSI32 | PC with Definicon DSI-32 coprocessor board |
| DSI780 | PC with Definicon DSI780 or PM030 coprocessor board |
| S375 | Symmetric 375 NS32016 based UNIX micro-computer |
| SUN3 | Sun-3 Unix workstation using Motorola 68020 processor |
| SUN4 | Sun-4 Unix workstation using SPARC RISC processor |
| HP9000-500 | Hewlett-Packard 9000 series 500 UNIX based mini-computer |
| HP9000-800 | Hewlett-Packard 9000 series 800 UNIX based RISC computer |
| MASSCOMP | Masscomp workstations and micro-computers |
| CLIPPER | Intergraph Interpro workstations using Clipper processor |
| VAX | Any member of the DEC/VAX family of computers |
Any version of E2XFBANK can perform transformations between any of these host formats. At present the E2XFBANK is available on PCs and on most UNIX systems supported by EMME/2. Thus, the transformation of a data base to and from VAX/VMS format is done on the other host. On VAX systems, a new utility program CHRECL is available which is used to transform the internal record structure of the data base files which have been uploaded from other systems.
The E2XFBANK does the data base transformation in situ, i.e. the data base file is transformed directly in place, without the need for copying it onto another file. This allows the transformation to be carried out even on the largest possible data bases, regardless of the amount of free disk space remaining on the disk. Of course, this also means that it is essential to back up the data base before starting the transformation process since a power failure or hardware failure during the transformation would leave the data base in an in-between state, no longer usable by either host system.
E2XFBANK takes as arguments two host identifiers which specify the type of transformation to be performed and the name of the EMME/2 data base file. In a first step, E2XFBANK performs a detailed test to check the structural integrity of the data base, followed by an analysis to verify that the current host type indeed corresponds to the input host which was specified. Only if these tests do not unveil any problem, the actual transformation is started. Depending on the size of the data base and the differences between the two host types regarding byte ordering, floating point format and device numbers, the time required for the transformation may vary from almost instantaneous to a few minutes. After this transformation, the data base is now ready to be used with the EMME/2 system on the new host.
The availability of the E2XFBANK utility makes upgrading from one type of system to another a very simple task. Data bases no longer need to be rebuilt on the new system, but can be used with no further processing on the new host. Besides its obvious usefulness for those installations which upgrade their EMME/2 system to a higher performing computing platform, the E2XFBANK utility is equally useful for sharing data bases among users with heterogeneous hosts and, of course, for providing software support.
Since some time now, a pre-release version of E2XFBANK has been shipped along with all EMME/2 upgrades involving a change of host systems. Starting with the next official release E2XFBANK will be distributed along with the other utilities on the standard distribution disks or tapes. Please contact INRO Consultants if you require a pre-release copy of E2XFBANK for exchanging or sharing EMME/2 data bases with other users on different host systems.