![[Access to Wang masthead]](images/access88b.gif)
|
|
Exchanging VS data files with IBM systems via tape |
|
From "VS Workshop", Access to Wang, November 1988 |
|
| [ Prior Article ] [ Return to the Catalog of articles ] [ Next Article ] | |
In keeping with this month's theme of communication with other systems, I'd like to cover another form of communication: that of exchanging data via tape. Specifically, I mean interchange using IBM tape formats on reels.
Why IBM? Why not other tape formats? The simple answer lies in the pervasive nature of IBM systems and the needs of all other manufacturers to meet that standard. IBM tape formats are supported by virtually all manufacturers, so they represent a common interchange path between all. And unlike disk formats - which vary with every manufacturer - tape formats are truly interchangeable. (The exception to this is in cartridge tape formats, which can vary as much as diskette formats.)
Some of the reasons you might need to exchange data on IBM-format tapes include:
You need to send tax or Social Security data to the government.
Accounts Payable check reconciliations have become a major headache. Your bank can provide a tape of information on returned checks, allowing automation of the process.
The volume of your print files has exceeded available storage and you wish to convert these reports to microfiche. The service bureau you work with needs an IBM tape.
The parent company in your organization uses IBM equipment and you need to send them your financial reports every month.
You wish to take advantage of your bank's Automated Clearing House (ACH) capabilities to provide automatic withdrawal service to your customers. (Ironically, the bank that accepts our IBM-format ACH tapes happens to be processing them on another VS!)
Other than ACH and other bank-related applications, the predominant need is for exchange of print files. As you will see below, this is a reasonably straightforward process.
Several items must be considered when attempting communication using IBM data formats. First, the types of files you can exchange on tape are generally limited to print files or consecutive files. Other file organizations - such as indexed and alternate indexed - are supported in very different ways in other architectures and cannot be directly translated. Again, the overwhelming need is to exchange needed include print files, so this limitation is rarely a problem.
Another consideration is the sort order of the data. IBM systems use the EBCDIC (Extended Binary Coded Decimal Interchange Code) character set, while the VS and many other manufacturers use the ASCII (American Standard Code for Information Interchange) character set. (There is also a third character set - Binary Coded Decimal (BCD) - that is rarely encountered.) The numeric value of characters under these schemes varies considerably; hence, the sort order would as well. For example, consider the decimal values of a few characters:
Character ASCII
ValueEBCDIC
Value(space) 32 64 $ (dollar sign) 36 91 1 49 241 A (upper-case A) 65 193 a (lower-case A) 97 129 From this list you can see that EBCDIC will sort numbers higher than upper-case letters and lower-case letters lower, exactly the reverse of ASCII. Obviously, reports sorted under each character set will be in different order. This may be a problem if the data is expected in a particular order by users in both environments.
Wang meets these needs with SORTINT, a variation of the SORT utility that allows the use of a translation table for the sort process. With SORTINT, sort fields are converted internally to another character set for sort purposes, but remain the same otherwise. ASCII conversions to EBCDIC are a direct SORTINT option; other tables can be created and maintained using the STABLEMT utility. (By the way, the version of SORT distributed with 7.13 of the operating system provides table processing and functionally replaces SORTINT. The name of the table editing program has been changed to TABLEDIT under this release.)
If you are developing your own programs, the COBOL sort options also support alternate character sets. Refer to the COBOL manuals for further information.
Like all tapes, IBM-format tapes must be initialized. Use Wang's TAPEINIT utility for this purpose, selecting the 'IL' (IBM label) option. You must also choose the tape density, a measure of the amount of data bits per inch of tape. 1600 bits per inch (BPI) is the most common, though many users have moved to 6250 BPI and some archaic government agencies are still working with 800. The densities available for your use are a function of the type of tape drive you have, but 1600 BPI is the common ground for most reel-to-reel tape applications.
After the tape is formatted properly, you could use a variety of methods to get files properly moved and converted to IBM format. Wang's TAPECOPY utility is the easiest for data files; use the ISWU PRINTVS and PRINTIBM utilities (described below) for print files.
The TAPECOPY utility copies files to an IBM format tape, optionally invoking the Wang TRANSL utility (a character conversion tool) to convert the character set to EBCDIC. Within TRANSL, the conversion can either be for the entire record area or individual areas. Output options include use of a file sequence number as an alternative to a file name and the label type (IBM label in this case).
A warning: TAPECOPY is not for the casual user. Users need to be aware of field lengths, data blocking, compression, block size, and many other technical parameters. If you are working to meet an external standard - such as the bank's ACH format - the technical specifications should be clearly understood and the results tested prior to use. In any case, the process should be run from a procedure to avoid typing errors.
In contrast to data files, moving VS print files to and from IBM format is simple. You should have the ISWU (International Society of Wang Users) PRINTIBM and PRINTVS utilities. These programs allow you to convert VS print files to IBM print format and back again, with simultaneous conversion to EBCDIC characters. PRINTVS converts VS disk files to IBM format and can write to disk or tape; PRINTIBM does the reverse, converting IBM print files on tape or disk to VS disk files. Both can read tape using either the file name or the tape sequence number.
If you would like to see the results of your copies to tape, the ISWU TAPEDUMP utility is what you need. TAPEDUMP prompts for the number of tape blocks to be examined, then produces a listing showing the contents of those blocks. This listing shows both characters and the hex equivalents, and you can specify which character set (ASCII, EBCDIC, or BCD) you wish to use. I use TAPEDUMP to check the contents of any tape of unknown origin, since it can be used with very little information on the contents of the tape. You will need version 3.03.00 (the version presently distributed by ISWU) to support 6250 BPI tapes.
In the January column, I mentioned the use of a non-Wang cable multiplexor (see "VS Peripheral Connections", January 1988 ACCESS 88; page 12-13). Recently I've heard of some difficulties in using these units with future operating system. Specifically, users were unable to use the devices under operating system 7.19, a pre-release version of 7.20. If you are interested in using these multiplexors, you should take this issue up with Wang and Fibronics (the manufacturer).
It also appears that the protocol converter I spoke of in the May column (see "Making Contact", ACCESS to Wang, May 1988; page 20) is no longer made. The distributor suggested use of conversion programs (software) rather than the hardware-based conversion approach of the protocol converter. The net effect to you is you won't have the opportunity to beat your head against the wall like I have trying to keep the finicky thing alive and communicating. Pity.
Next month we'll cover some advanced uses of Multi-Station's glossary language for operations automation.
PRINTIBM, PRINTVS, and TAPEDUMP are available from the International Society of Wang Users (ISWU). ISWU Software Library; Wang Labs; One Industrial Ave., MS 019-350; Lowell, MA 01851; 617/967-1058. (ISWU membership is required.)
TAPEINIT and TAPECOPY are Wang system utilities bundled with the operating system. Both are covered in the System Utilities Reference (Publication 800-1303-04) and in the System Utilities Reference - Release 7 Series (Publication 715-0421A).
Copyright © 1988 Dennis S. Barnes
Reprints of this article are permitted without notification
if the source of the information is clearly identified