Converting Files to the PC Platform

DISC can convert hundreds of foreign file types to many different types of PC files.  This article briefly discusses some of the PC file type and media choices you have.  For brevity, we have chosen to only discusses common data formats on this page; if you need to convert to another file type, please contact us.

PC Media Choices

When converting files to a PC, the preferred media is usually floppy, CD, or DVD.   We write most jobs to CD or DVD, but for very small files, a PKZIP file on floppy disk is the least expensive media.  The CD is a good choice for most jobs, holds a respectable 650 MB, can't be accidentally erased, and is not prone to all the software version issues and drive issues of tape backup programs.  For files over 650 MB either a DVD or a PKZIP file on CD is preferred.

Files over the 4.7 GB capacity of a single layer DVD can be written to a double layer DVD, or can be compressed with PKZIP to fit on a single layer DVD. Files even larger than that can be accommodated by spanning a PKZIP file across multiple DVDs; files over 100 GB can be delivered that way.  Even larger jobs can be delivered on a USB or Firewire external hard drive. If you are converting files over 2 or 4 GB, please be sure to read our article PC Large File Limitations.

DISC can also write dozens of other disk and tape formats, but the cost is generally higher, and there are potential complications with tape formats.  If you prefer tape, please contact us.

Small files, rush jobs, and weekly jobs are often sent electronically via either email or ftp

Types of PC Data Files

Excluding proprietary files like Access, dBASE, SQL, etc., there are four types of PC data files that are very common, and a few that are less common.  They are:

• Fixed field with no record delimiter: All the fields are of a fixed size, and therefore the records are all the same size. This file has no field or record delimiters.  This is often a good format for languages like c, FORTRAN, BASIC, Pascal, COBOL, etc.
• Fixed field with record delimiters: All the fields are of a fixed size and the records are the same size, like above, but the records are delimited, usually with CR-LF. This is a good format for most database programs, and some languages.
• Comma delimited: Also called CSV -- Comma Separated Variables-- the fields in a comma delimited file are delimited (separated) with commas, and the records are delimited with CR-LF.  Character fields may be enclosed in double quotes ("), but numeric fields may not. If a character field is enclosed in quotes, it may contain a comma, otherwise it may not.
• Tab delimited: The fields are delimited with tabs and the records are delimited with CR-LF.  Fields are not enclosed in quotes, and commas are allowed in the data. Tab delimited files are more common on Macintosh than on MSDOS or Windows.
• Other file types: There are several less common methods of storing data, such as DIF.  UNIX commonly uses the vertical bar (|) as a field delimiter, and indeed almost any character can be used as a delimiter.  Some mailing list program store each field on a separate line, and always write the same number of lines per record.  These are generally not preferred formats for exchanging data because they are not universally understood, and may require additional conversion effort.

Most PC database programs can import comma delimited files, and many can import fixed field with record delimiters.  Most cannot import fixed field without record delimiters, which is exactly the type of file found on most large computers -- mainframes and minicomputers. Therefore, when we convert from a mainframe tape to a PC file, we usually append a CR-LF to the end of each record.  In order to do this, we need to know the record length.

Because mainframe files are in a fixed field format, the least expensive conversion is to keep them that way, adding a CR-LF record delimiter if needed.  But if your program can't read fixed field, we can convert the file to a delimited format. This requires writing a simple program that reads in the fixed field data and writes it back out with field delimiters.  It adds somewhat to the cost. We will require a record layout from you to do the conversion.

Database Programs

Most of the conversions we perform will end up in a PC database, such as Access or dBASE.  The most cost effective way to accomplish this is usually for DISC to convert your data to one of the file types above, which you then import into your preferred database.  This gives you control over such things as the field names.  DISC has written several technical articles to assist you with the conversion. These articles are in our Tech-Talk section. See "Additional Information" below.

DISC can also import files directly into some database applications, saving you the time and aggravation of keying and testing the layout.  We currently offer direct conversion to dBASE, Foxpro, and Access.

Other Applications

If you need to import data into another application, such as a mailing list manager, check the manual for which file types the program can import.  Chose the method that is closest to the original file type.  For example, if you have a mainframe tape containing fixed field records, see if the program can import fixed field.

Many types of files can be imported into spreadsheets, but be aware of the limitations of a spreadsheet for data files.  Spreadsheets are designed to be used as, well, spreadsheets, not databases.  They don't have all the functions of a database program, such as record and field selection, indexing and sorting, and output formatting.  Also, spreadsheets try to fit the entire file into memory, so the number of records they can handle is limited to the memory available.

Conversion Issues

The issues you will encounter in your particular conversion depend on what you are converting from and to.  Mainframe files are commonly stored in EBCDIC, and often have binary or IBM Signed fields, and other issues.  If you are converting from this type of file, you might want to review some of our technical articles listed in the TechTalk section, especially Mainframe to PC Data Conversion Issues. There are several articles on mainframe data types and files, and a seven-part series on COBOL files.

Additional Information

For more articles on data conversion, see our TechTalk Index.